Note: Descriptions are shown in the official language in which they were submitted.
PATEN~
333-2052
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~` BACKGROUND OF THE INVENTION
The invention relatcs to systems and methods for
color correctin~ video picture signals. ~ore particularly,
the present invention pertains to improved systems and
methods for increasi~g the quality and speed of color
correction op~rations. This patent application describes
improvem~nts upon the color correction systems and methods
disclosed in V.S. Patents No. 4,096,523 (the "~ainbow"
patcnt); No. 4,223,343 (the "Anamorphic" patent); ~o.
4,410,908 (the "Luminance" patent); commonly owned U.S.
Paten~ No. 4,679,067, entitled ~Color Correction System and
Method With Localized Color Sampling~; Patent No. 4,694,329,
entitled "Color Correction System and Method With Scene-
Change Detection"; and Patent No. 4,750,050, entitled
~Editing System and Methodll.
There i8 a continuing need to improve the efficiency,
6peed, and qual$ty of the color correction of video picture
signals, especially in film-to-tape and tape-to-tape
~! transfers, and particularly in scene-by-scene color
correction. For instance, there i8 a need to better isolate
- particular ob~ects for color correction. Furthermore, there
i8 a need to better select a specific color or a specific
range of colors for color correction.
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Accordingly, an ob~ective ~s to
satisfy the above needs ~nd prov~de a ~y~tem and method for
color correct~ng video p$cture signals with lncreased
eff~ciency, ~peed, ~nd qu~l~ty.
Another ob~ective i8 to provide an
apparatus ~nd a method for improving the accuracy with which
a specific color or a ~pecific range of colors may be color
corrected.
An additional ob~ective i8 to
- provide an apparatus and a method for more easily
identifying and recall~ng the color corrections associated
with particular scenes ~n an ~mage recording medium that is
to be color corrected.
s A further ob~ect~ve i8 to provide an ;o prov~de an
apparatus and a method for better segregat~ng ~ particular
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area of the picture produced by the video p~cture signals
and color correcting this particular area. It is a further
object to ~lend the edges of the area into the remainder of
the picture and make the edges less noticeable.
Yet another ob~ective is to provide 5 to provide
an apparat~s and a method for improving the ability to color
correct color signals having certain levels.
SUMMARY OF THE INVENTION
According to one aspect of the invention there is
provided a video signal color correction device comprising, in
combination, a video picture comparison device, said comparison
device including means for conducting signals to display means
for displaying two different pictures formed from two different
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video signals, video signal processing means for converting
video signals into a form suitable for storage, means for
conducting both of said video signals to said video signal
processing means, storage means, means for storing one of said
video signals in said storage means after processing by said
signal processing means, readout means for reading said one
signal out of said storage means and delivering it to said
display means, and means for conducting the other video signal
from said signal processing means to said display means, thereby
avoiding differential degradation of said two different video
signals; and color correction means for correcting the color of
at least said other signal.
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q According to another aspect of the invention there is
provided apparatus for facilitating color comparison of a
~ plurality of video pictures, comprising: digital random-access
~ video memory means for storing and recalling signals
representative of said plurality of video pictures, including
~` the current picture in a sequence; control means for controlling
said video memory means for selectively storing signals
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representative of selected ones of said video pictures and for
selectively recalling the stored signals; display means,
responsive to said control means, for displaying a first video
picture corresponding to said current video picture and for
displaying a second video picture corresponding to the recalled
signals representative of another video picture, whereby said
first video picture, corresponding to said current video
picture, and second video picture, corresponding to said other
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fir~t video picture, corresponding to said current video
picture, and second video picture, corresponding to said other
video picture, are readily comparable; and color correction
means for selectively generating color correction signals for
said plurality of video pictures, wherein said video memory
means is responsive to said color correction means and stores
signals representative of a plurality of color-corrected video
pictures.
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According to a further aspect of the invention there
is provided a method for color-comparing a plurality of video
pictures corresponding to signals produced by a video signal
source, comprising the steps of storing in a digital random-
access memory signals representative of a video picture
currently produced by said video signal source; recalling the
stored signals representative of said current video picture;
selectively storing in said digital memory signals
representative of another video picture produced by said video
signal source; selectively recalling the stored signals
representative of said other video picture; displaying first and
second video pictures on a monitor, said first video picture
corresponding to the recalled signals representative of said
:
current video picture, said second video picture corresponding
to the recalled signals representative of said other video
picture; and selectively color correcting the signals produced
by said video signal source, and the step of storing color-
corrected signals representative of color-corrected video
pictures.
According to a further aspect of the invention there
is provided a color correction system for color correcting video
picture signals represen~ative of images stored in an image
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recording medium, comprising color correction means for
selectively generating color correction siqnals for at least one
selected image of each of a plurality of scenes recorded on said
image recording medium; video stoxage means for storing signals
corresponding to a plurality of images, said video storage means
being responsive to said color correction means and being
adapted to store color-corrected signals; control means for
selectively storing signals representative of a desired image in
said video storage means and for selectively retrieving the
stored signals representative of said desired image from said
video storage means, said control means including means for
automatically storing signals representative of a currently
produced image from said image recording medium and for
automatically retrieving the stored signals representative of
said currently produced image; and display means, responsive to
said video storage means, for displaying a plurality of video
pictures, wherein one of said displayed video pictures is formed
from the retrieved signals representative of said currently
produced image and another of said displayed video pictures is
formed from the retrieved signals representative of said desired
image.
In a further aspect of the invention there is provided
a method for color correcting video picture signals
representative of images stored in an image recording medium,
comprising the steps of producing video picture signals
representative of each of the images stored in the image
recording medium; selectively generating color correction
signals for at least one selected image of each of a plurality
of scenes recorded on said image recording medium; selectively
storing signals represantative of a desired image in a digital
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random-access video storage device; selectively retrieving the
stored signals representative of said desired image from said
video storage device; automatically storing signals
representative of the current ima~e within said image recording
medium in said video storage device; automatically retrieving
the stored signals representative of said current image from
said video storage device; and displaying on a monitor one video
picture formed from the retrieved signals representative of said
current image and another video picture formed from the
retrieved signals representative of said desired image.
A still further aspect of the invention provides an
apparatus for facilitating comparison of one video picture with
another video picture selected from a plurality of other
previously-stored video pictures, said apparatus comprising, in
combination, first input terminal means for receiving signals
representing said one video picture; digital random access video
picture signal storage means; second input terminal means for
receiving and storing in said storage means digital signals
representative of said other video pictures; retrieval means for
randomly retrieving from said storage means signals
representative of a selected one of said other pictures; display
means for displaying video pictures; signalprocessingmeans
for processing video signals into a form suitable for display on
said display means; means for conducting the signals
representative of both said one picture and said selected other
picture through said signal processing means to said display
means; and control means for causing the display of said one
picture and said selected other picture adjacent one another on
said display means, whereby said one picture and said selected
other picture can be easily compared without differential
degradation of the pictures.
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A further aspect of the invention provides a method of
displaying video pictures to facilitate comparison with one
another, said method comprising the Rteps of storing a plurality
-: of pictures in digital signal form in a random-access digital
video picture storage device, randomly retrieving from said
- storage device the signals for a selected one of the stored
picture~, presenting, from a separate source, video picture
signals representing another video picture, processing both the
: signals for the selected stored picture and the video picture
signals for said other picture in the same way to prepare said
signals for delivery in proper form to operate video display
means, and utilizing the processed signals for displaying said
selected stored picture and said other picture near one another
to facilitate comparison of said pictures with one another
i~ without differential degradation.
Also disclosed herein is an apparatus in which a
predetermined range of colors around an infinitely variable
principal color are selected. Color correcticn~
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for the video picture slgnals corresponding to the
predetermined range of colors are selectively developed, and
then the color correct~ons are applied to the video picture
signals, thereby producing color corrected vi~eo picture
signals. Accordingly, any object in the video p~cture may
be selected based upon its color. Preferably, the size of
the predetermined range of colors i8 adjustable. Therefore,
all of the colors in the o~ject may be selected for color
correction, even if the object consists of a wide range of
colors. However, the range may be adjusted to be very
narrow, if the operator so desires, and this can be done
substantially independently of the saturation of the colors.
Thus, particular ob~ects may be selected for color correction
based upon their colors. The principal color may be selected
from any hue, regardless of the saturation levels. This
advantage results in an improvement in the quality of the
color corrected videotape. Noreover, this advantage decreases
the time, and therefore the cost, of color correcting motion
picture film and videotape.
A color corrector may include circuits for
discriminating the video picture siqnals in a specific area
- from the video picture signals forming the remainder of the
.picture. Color correction signals are applied to the video
picture ~ignals either inside of or outside of the specific
area.
Preferably, the edges of the area are formed so
that the area blends well with the remainder of the picture.
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~h~s can be done, for example, by using a l~near dissolve to
form the edges of the area.
~ he size and/or the posltion of the specific area
may be changed at the beginning of each new 8cene or frame.
Consequently, the area may Ufollow~ a particul~r object as
it moves from place to place in successive frames or scenes.
Hence, greater object selectivity for color corrections is
obtained, and better color corrections are developed.
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The color corrections for a partLcular scene may be
identified or labeled with a video picture from that
particular scene. The video picture is displayed for the
operator, preferably on an auxiliary monitor scrcen, or on
the main monitor screen. The operator may use the display
to recall the color corrections for that partisular scene
and apply them to the video picture signals for the present
scene. Several video pictures may be shown on the same
di~play, and the operator may utilize an array of
pushbuttons arranqed like the video pictures on the screen
or a light pen in order to choose the color corrections to
be recalled.
Altcrnatively, the display may include a "touch
screen,~ and the operator may touch the video picture
associated with the desired color corrections in order to
recall them. Numerical data giving locations of the
corrections for prior scenes preferably are displayed next
to the pictures on the auxiliary display. Thu~, the
operator also can usc the numerical correction location
information displayed next to each picture to rctrieve the
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associated correction value~. The operator doe6 not have to
remember the scene number for the particular ~cene, wh$ch
may change as the motion p$cture f~lm or the videotape is
edited. The operator can then readily identify, locate, and
recall the color corrections he or 8he de~ireg to work with.
This greatly increase~ the speed with which a motion picture
film or a videotape may be color corrected.
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The color corrector may include circuits for
discr$minat~nq video p~cture 3ignals based upon their color
levels. Specifically, such discrimination circu~ts may
discriminate signals above a predetermined level or signals
below a predetermined level or ~ignals between two
predetermined levels. Color corrections are selectively
developed for the discriminated signals, and the color
corrcctions are applied to the associated video s~gnals to
produce color corrected video picture siqnals. This aspect
of the invention further increases object selectivity and
speeds the color correction process.
The features outlined above each increase the
efficicncy of the color correction process. In addition,
when two or more features are used together, even greater
efficiency results, such efficiency previously being
unattainable.
BRIEF DESCRIPTION OF THE DRAI~INGS
The above and other objects, featur¢s, and advan-
tages of thc present invent$on will becomo apparent upon
cons$dcration of the following dctailed description of
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1 3 2 6 2 8 8 PATENT
333-2052
illustrative embodiments thereof, especially when taken in
conjunction with the accompanying drawings, wherein:
. Figure 1 is a diagrammatic illustration of a color
.~ correction system according to the invention
Figure 2 is a top plan view of the front panel for
the color corrector shown in Figure l;
- Figure 3 is an enlarged view of a portion of the
front panel shown in Figure 2;
Figure 4 is an enlarged view of another portion of
the front panel shown in Figure 2;
Figures SA-5D are diagrammatic illustrations of
waveforms on a vectorscope and depict the functions of the
` variable vector controls;
. Figures 6A-6C are enlarged views of the auxiliary
monitor and the main monitor for the color correction system
shown in Figure l;
Figures 7A-7~ are a block diagram of the color
correction circuits in a color correction system according
, to the invention;
~`, Figure 8 is a block diagram of the variable vector
. control circuits for a color correction system according to
the invention;
~` Figure 9 is a block diagram of a coefficient
processor for the variable vector control circuits illus-
trated in Figure 8;
. Figure 10 is a schematic diagram for the level
discrimination circuit illustrated in Figure 8;
Figures llA-llC are waveform diagrams for the
level discrimination circuit illustrated in Figure 10.
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Figure 12 is a vector diagram representing some of
the variables in the operation of the device shown in Figure
8;
Figure 13 i~ a schematic circuit diagram of a
` component of the device shown in Figure B;
Fi~ure 14 is a diagram illustrating the
operational characteristics of a typical prior art device;
Figures 15A-15D are waveform diagrams illustrating the
principles of operation of the circuit of Figure 8: and
~; Figures 16 and 17 are flowcharts of steps in
computer programs that may be employed to implemen~ the
nCall-A-Picture" feature of the invention.
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DETAILED D~SCRIPTION OF THE PREFERRED EMBODI~5ENTS
General Description
Figure 1 shows a color correction system 10
constructed according to the invention. The color
correction system 10 includes a color corrector 11 having a
front panel 12. Portions of the front panel 12 are
illustrated in greater detail in Figures 2-4. The front
panel 12 has a set of variable vector controls 14 and a set
of six vector controls 16. The six vector controls 16
function as outlined in the Rainbow and Luminan~e patents.
Referring now to the lower left-hand portion of
Figure 2, the front panel 12 includes a set of color balance
contro!s 18 and "window" controls 20. The "window~ controls
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20 are described and depicted in greater detail in
Patent No. 4,679,067 as well as Patent No. 4,694,329.
The front panel 12 additionally includes video si~nal
30urce controls 22. The video ~ignal source controls
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1 3 2 6 2 8 8 333-2052
22 adjust parameters such as the PEC gain and negative gain
for each of the red, green, and blue channels. Moreover,
the video signal ~ource controls adjust other parameters,
for instance, the horizontal pan, the vertical pan, the
zoom, and the contours. Each of the controls in the sets of
controls 14, 16, 18, and 22 includes a control knob which is
coupled to a shaft-position encoder, as described in
Patent No. 4,679,067 and Patent No. 4,694,329.
The right side of the front panel 12 includes
~ushbuttons and displays. Specifically, this portion of the
front panel includes two rows of pushbuttons 24, which are
.,
shown in greater detail in Figure 4, and three rows of
pushbuttons 26, which are shown in greater detail in Figure
3. The functions of many of these pushbuttons are described
in the Rainbow and Luminance patents. A display 28 (Figure
4) shows the scene number for the color corrections stored
in the A buffer and the B buf'er. Moreover, the display 28
shows the scene numbcr for the current scene.
Still referring to Figure 4, a keypad 30 and a
display 32 are used to recall the color corrections for a
particular scene and apply them to the present scene. For
example, if the operator wanted to use the color corrections
for scene number 1,234 for the current scene, the operator
would prcss the "call" pushbutton in the upper one of the
rows 24 and then the buttons 1, 2, 3, and 4 of the keypad 30
in this sequence in order to recall the desired color
corrections.
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PATENT
333-2052
Also shown in Pigure 4 is an array 34 of
push~uttons and a row of pushbuttons 36 for use in the
"Call-A-Picture" feature of the invention, which feature is
used for recalling color correction signals for previous
scenes in another manner. The operation of ~he
"Call-A-Picture" feature will be described in detail below.
The portion of the front panel 12 shown in Figure 3 has
waveform pushbuttons and indicators 38 for selecting various
waveforms for viewing on an oscilloscope (not shown) as well
as monitor selector pushbuttons and indicators 40 for
selecting various signals for monitoring.
Referring again to Figure 1, the system 10 has a
computer 42, which is connected to each of the color
corrector 11, a video signal source 44, a videotape recorder
46, and a video memory 48. The video signal source 44 may
be a film chain or telecine, a videotape player, or the
like. The video signal source 44 produces video siqnals
from the associatcd image recording medium. These video
signals are delivered to the color corrector 11 so that they
can be corrected. The color corrector 11 provides color
corrections for the video signals from the video signal
source 44 under the direction of the operator and the
computer 42, and it produces color corrected video signals.
The color corrected video signals are sent to a main monitor
50, and, at the appropriate time, to the videotape recorder
46. The operator may observe the effect of the color
corrections on the video signals by looking at the video
picture on the main monitor 50. The videotape recorder 46
records the color corrected video signals on a vidcotape 54,
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1 ~62~ PATENT
333-2052
usually during a second run after color corrections have
been made during a first run, thereby producing a color
corrected videotape.
The main monitor is shown with windows Wl and W2.
The use of the windows W1 and W2, which are movable in size
and/or position, is described further below.
An auxiliary monitor 52 iS connected to the
computer 42. The auxiliary monitor 52 displays a plurality
of video pictures, such as the video pictures 56a-56d. The
function of the auxiliary monitor 52 and the video memory 48
is described below during the discussion of the
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~Call-A-Picture" feature.
Referring now to Figure 2, above each of the
control knobs in the sets of controls 14, 16, 18, and 22 is
a horizontal linear group 35 of four light-emitting diodes
("LEDs"), which are referred to as ~rangefinder" LEDs. The
two inner LRDs of each group 35 are green, while the two
outer LEDs are red. When the associated control knob is in
its center position, the two inner LEDs are energized. If
the control knob is turned to the right, the two inner LEDs
are deenergized and the rightmost LED is energized.
Correspondingly, if the control knob is turned to the left,
the two inner LEDs are deenergized, and the leftmost LED is
energized. Accordingly, the operator may quickly determine
the position of any of the control knobs.
Resct buttons 64, 66, and 68, are provided to
permit the operator to readily center the control knobs in
the sets of controls 16, 18, and 22, respectively.
Specifically, the operator presses a reset button, and all
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PATENT
333-2052
of the control knobs in the associated set of controls are
electronically centered by zeroing the counter connected to
the control knob. The controls 16, 18, and 22 include
active memory pushbutton-indicators 70, 72, and 74,
respectively.
Referring now to the lower part of Figure 4, the
"notch" pushbutton sets the scene boundary between scenes;
that is, pressing the "notch" button stores the frame number
of the first frame of a new scene. The "color correct
enable" pushbutton in the same row makes the ~notch"
pushbutton effective for color correction events. The "pan
enable" pushbutton makes the "notch" pushbutton effective
for position related events, such as horizontal pans,
vertical pans, and zooms.
The ~carry forward mode" is entered by pressing
the "carry forward mode" pushbutton in the upper row 24. In
this mode, the color corrections from the last scene are
carried forward for the next scene. That is, once the
operator establishes color corrections for a particular
scene and then sets the scene boundary between that scene
and the next scene, these color corrections are both stored
for the particular scene and applied to the next scene.
Thus, the operator may use these color corrections as a
basis for color correcting the next scene.
The "picture file" pushbutton is used with the
video scene recall feature, i.e., the "Call-A-Picture"
feature of the invention, which is described below. The
~picture file" pushbutton enables the array of pushbuttons
34 and the row of pushbuttons 36.
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1 3262~ PATENT
333-20~2
The "diss. n pushbutton is used to produce a linear
transition between the color corrections for a given ~cene
and the color corrections for the subsequent scene. For
example, the operator may make color corrections for a given
scene and then make color corrections for the 6ubsequent
scene. If the operator wants a smooth transition between
scenes, the operator presses the "dissolve" pushbutton at a
frame near the end of the given scene and again presses the
"dissolve" pushbutton at a frame near the beginning of the
subsequent scene. The computer is programmed to
automatically provide a linear transition, for ins~ance, on
a frame-by-frame basis, between the color corrections for
the given scene and the color corrections for the subsequent
scene for all frames between the two dissolve points.
The "source 1," nsource 2 ~ n "source 3, n and
"source 4" pushbuttons, which are shown in row 26a of Figure
3, enable the opcrator to select one of a variety of video
signal sources. For example, the operator may select a
telecine as the video signal source by pressing the "source
1" pushbutton, or select a videotape player as the video
signal source by pressing the "source 2" pushbutton.
The ~load count" pushbutton (next to the "source
4" button) allows the frame counter to be initialized to any
number at the beginning of a new job. The "count mode"
pushbutton allows the operator to select among various
counting modes for the frame counter, such as, counts by
hours, minutes, scconds and film frames; or PAL video
frames; or NTCS video frames.
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The "matte ext," "variable vector matte on, n n six
vector matte on," and "matte store" pushbuttons are de-
scribed below during the description of the "Traveling
;; Matte" feature of the invention.
The "disc load," "disc save," ~disc format,n "auto
save," and "disc test" pushbuttons are utilized to control
; an external storage device (not shown) for the computer,
such as a floppy disc drive or a hard disc drive.
Variable Vector Controls
The upper left-hand portion of Figure 2
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illustrates the set of variable vector controls 14. ~he
controls 14 include a variable vector position control 80, a
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~ delta control 82, a factor control 84, a saturation control
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86, a hue control 88, and a luminance control 90.
Furthermore, the variable vector controls 14 include a "set
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up" pushbutton 92, the function of which is described below.
- A ring of LEDs 94 is located around the circumference of the
' variable vector position control 80. The LEDs 94 indicate
~ the angular orientation of the variable vector position
,,,.A, control 80. The angular orientation of the variable vector
position control 80 corresponds to one of the colors on a
vectorscope.
The variable vector position control 80 is used to
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select a particular range of colors for color correction.
- The principal color within the xange of colors is determined
by the angular orientation of the variable vector position
control 80. The variable vector position control 80 may be
used to select any principal color within the precision of
the associated counter. For example, if the associated
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1 3 2 6 2 ~ (3 PATENT
counter is a 12-bit counter, any one of 4,096 different
principal colors may be selected with the variable vector
position control 80. Thus, the principal color is
essentially infinitely variable.
The functions of the various controls 80-90 are
better explained in conjunction with Figures 5A-5D. The
circle 96 in Figures 5A-5D diagrammatically illustrates a
vectorscope screen. The waveform 98 illustrates the
response of the variable vector control circuits when the
input signal to the color corrector is from a device which
generates a spectrum of color signals, that is, a signal
whose color varies throughout the visible spectrum. The
angular orientation of the waveform 98 corresponds to a
given angular orientation of the variable vector position
control 80. Figure 5A shows the effect of turning the
variable vector position control 80. For example, if the
control 80 is turned clockwise from the position of waveform
98 to select a different principal color, the response of
the vectorscope becomes the waveform 98a. Then, if the
control 80 is turned further clockwise to select another
principal color, the response of the vectorscope becomes the
waveform 98b. Similarly, if the control 80 is turned
counterclockwise to select yet another principal color, the
response of the vectorscope becomes the waveform 98c.
Accordingly, the control 80 may be turned to select
virtually any hue as the principal color.
The variable vector controls are nominally effec-
tive for a predetermincd range of colors around the
principal color. For example, colors within plus or minus 5
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1 3 2 6 2 ~ ~ 333-2052
degrees of the principal color will be color corrected along
with the principal color; however, the e~fectiveness of the
color corrections will decrease as the angular distance from
the principal color increases.
The delta or bandwidth control 82 is provided in
order to adjust the width of the predetermined range of
colors effected by the variable vector control position
control 80. Figure 5B shows the effect of rotating the
delta control 82. The delta control 82 may be rotated
clockwise in order to increase the width of the range of
colors or rotated counterclockwise in order to decrease the
width of the range of colors. Hence, the width of the range
of colors may be made as large or as small as the operator
desires, within the limits of the equipment. For instance,
the width of the range of colors may be changed anywhere
from plus or minus about 2 degrees around the principal
color to plus or minus 90 degrees around the principal
color. Figure 5B shows a waveform 100 with the same
principal color as the wavcform 98 but with an increased
.:
bandwidth ~a 2." The waveform 100 was obtained b~ turning
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the delta control 82 clockwise. Figure 5B also shows a
waveform 102 with the same principal color as the waveform
98 but with a decreased bandwidth ~a 3." The waveform 102
was obtained by turning the delta control 82
counterclockwise.
Once the desired principal color and the desired
range of colors around it have been selected with the
variable vector position control 80 and the delta or
bandwidth control 82, the saturation control 86, the hue
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control 88, and the luminance control 90 may be employed to
generate color correction signals for the video picture
~- signals corresponding to the sclected range of colors. ~ore
particularly, the hue control 88 is used to alter the colors
in the selected range of colors and shift them in the color
spectrum, while the saturation control 86 is used to change
` the levels or intensity of the colors in the selected range
of colors. Additionally, the luminance control 90 is
utilized to vary the luminance or brightness of the colors
in the selected range of colors.
Figure 5C shows the effect of rotating the hue
control 88. To shift the colors in the selected range of
colors, the hue control 88 is turned clockwise or
counterclockwise. Figure 5C shows a waveform 104 and a
waveform 106. The waveform 104 was produced by turning the
hue control 88 clockwise after the waveform 98 was selected.
Similarly, the waveform 106 was produced by turning the hue
control 88 counterclockwise after the waveform 98 was
selected. The hue control may shift the color within the
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selected range of colors by any desirable amount, within thelimits of the equipment. For example, the hue control may
be designed to shift the principal color by up to 60 degrees
in one direction or the other.
Figure 5D shows the effect of turning the satu-
ration control 86. The saturation control 86 may be rotated
clockwise or counterclockwise to increase or decrease,
respectively, the saturation levels of the colors in the
selccted range of colors. As an example, the waveform 108
illustrates what happens when the saturation control 86 is
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1 3262~3 PATENT
333-2052
rotated clockwise once the waveform 98 has been selected.
The waveform 108 has a saturation level above that of the
waveform 98. The waveform 110 illustrates what happens when
the saturation control is rotated countexclockwise once the
waveform 98 has been selected. The waveform 110 has a
saturation level below that of the waveform 98.
The luminance control 90 may be used to increase
or decrease the brightness of the colors within the selected
range of colors. Of course, the luminance control 90, the
hue control 88, and the saturation control 86 may be
employed together to alter the associated parameters of the
colors within the selected range of colors. The variable
vector control knob 80 and the delta control knob 82 are
utilized to set the selected range of colors, as noted
above. The factor control 84 is used to select those colors
within the selected range of colors that have saturation
levels either above or below a specified level. The
function of the factor control 84 is described in greater
detail below during the description of Figures 10 and 11.
As an example of the use of the variable vector
controls 14, the color correction of a particular scene will
be described. Assume the sperator desires to color correct
a specific object, such as an apple appearing ir. a picture
on the main monitor 50. ~he operator initially presses the
"set up~ pushbutton 92, which is part of the variable vector
controls 14. This causes all portions of the picture which
have colors within the nominal range of colors ~et by the
variable vector position control 80 to become a neutral
gray. If the apple does not become grav, the operator
"6
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1 3262~ 333-2052
rotates the variable vector position control 80 until the
apple becomes gray. If only a portion of the apple becomes
gray because the apple contains colors outside of the
selected range, the operator rotates the delta control to
increase the delta or bandwidth of the selected range until
the entire apple becomes gray. This signifies that the
colors the operator desires to correct, i.e., the colors
forming the apple, are encompassed within the selected
range. The operator again presses the ~set up" pushbutton
92, and the colors are displayed in an unaltered fashion.
Alternatively, the "set up" button may be
connected so that objects with the selected color appear
normally on the monitor while objects having other colors
appear to be gray. The modifications to Figure 7A that are
necessary to implement this feature are readily apparent to
a person having ordinary skill in the art and, therefore,
will not be described in detail here.
Now, the operator may turn any or all of the
saturation control 86, the hue control 88, or the luminance
control 90 in order to adjust the corresponding parameter of
the colors within the selected range of colors. For
instance, the operator may rotate the hue control 88 to
change the color of the apple from a greenish red to red.
Once the operator has developed the color corrections with
the controls 86, 88, and 90, the operator causes the color
corrections to be stored in the computer 42. The storage
and retrieval of the color corrections may be accomplished
as described in the Rainbow patent. The color corrections
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1 3 2 6 2 ~ ~ 333-2052
are read from the memory in the computer and used to produce
the color corrected videotape 54 during the "run" mode.
In this manner, the video picture signals forming
the apple may be color corrected to produce a desirable
image. with the variable vector controls, the apple may be
segregated from any of the other objects in the picture and
then color corrected. Accordingly, the variable vector
controls permit greater object selectivity during color
correction and speed the color correction procedure. That
is, an object can be segregated from others having hues very
close to that of the selected object, or even from objects
having the same hue but a different saturation level. It is
. , ,
believed that the hue of the selected object can be closer
to that of other similarly colored objects and still be
effectively segregated for color correction purposes than
with prior color correction devices. This not only improves
the speed of color correction, but makes some color
- corrections possible for the first time, thus significantly
improving the color correction ~uality.
; Video Scene Recall ("Call-A-Picture") Feature
Referring now to Figure 4, pushbuttons 34 and 36,
together with the auxiliary monitor 52 shown in Figure 1,
may be used to implement the video scene recall or
"Call-A-Picture" feature of the invention. This feature
gives a miniature reproduction on the monitor 52 of a frame
from each of several prior scenes which have been
color-corrected. This allows the operator to visually
select the prior scene whose corrections are to be recalled
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1 3262~3 PATENT
333-2052
without running the telecine or tape player backwards or
using slow prior methods.
In the specific preferred embodiment shown in the
drawings, the auxiliary monitor 52 displays up ~o twelve
different video pictures, such as the video pictures 56a-56d
shown in Figures 1 and 6. The twelve video pictures are
displayed in an array with four columns and three rows.
Each of the twelve video pictures corresponds to one of the
twelve pushbuttons 34 shown in Figures 2 and 4. Each video
picture is associated with the color corrections for the
scene which includes that video picture, and each pushbutton
34 is associated with one of the video pictures.
Specifically, the pushbu tons 34a-34d correspond to the
video pictures 56a-56d, respectively. The pushbuttons
correspond to the video pictures based upon their placement
in the associated array.
When the operator desires to recall the color
corrections for the scene with the video picture 56b, for
example, the operator presses the pushbutton 34b, and those
color corrections are recalled and applied to the output of
the video signal source 44. The information for producing
the video pictures on the auxiliary monitor is stored in the
video memory 48. This information is recalled and directed
to the auxiliary monitor under the control of the computer
42. The video memory 48 can be any commercially available
video picture storage device. One such device which has
been used successfully is the Model ICB Image Capture Board
sold by AT~T, which is a digital device for storing and
retrieving video picture signals.
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1 32h2~
PATENT
- 333-2052
~ he video scene recall feature of the invention
enables the operator to quickly and easily determine and
recall particularly useful color corrections. The operator
does not have to remember what ecene corresponds to the
contents of buffer A or what scene corresponds to the
contents of buffer B. Moreover, the operator does not have
to think of a name for the color corrections for a given
scene and type it onto a display or write it down somewhere.
This feature of the invention presents the operator with an
easily recognizable label for specific color corrections.
Thus, the operator is better able to recall and utilize
previous color corrections. As a result, the time necessary
for color correcting a videotape is shortened. The video
scene recall feature is an alternative to the use of the
"call" pushbutton and the keyboard 30 for recalling previous
color corrections.
Figures 6A-6C show the main monitor 50 and the
auxiliary monitor 52 on a làrger scale than in Figure 1.
Figure 6A illustrates the auxiliary monitor S2 after the
operator has identified the color corrections for two
previous scenes. The operator has used video pictures 56a
and 56b for the identification of the color corrections. In
particular, the operator has identified the color
corrections for scene 0081 with a video picture
corresponding to a person's face, and the operator has
identified the color corrections for scene 0097 with a video
picture corresponding to a house. A different video
picture, i.e., a video picture from the current scene, is
displayed on the main monitor 50 in the lower lcft hand
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: t 32~2~,3 PATENT
333-2052
corner of Figure 6. The operator determines the color
corrections for the current scene, as set forth above and in
the Rainbow patent, and now wishes to identify those color
corrections for later use. The operator simply presses the
"store" pushbutton, which is located in the row of
pushbuttons 36 (Figure 4), and then the operator presses the
pushbutton 34c.
Figure 6~ illustrates what happens after the
operator presses these pushbuttons. The picture on the main
monitor 50 is displayed on the auxiliary monitor as the
video picture 56c, which corresponds to the pushbutton 34c,
and the scene number for the present scene, i.e., 0110, is
displayed in the auxiliary display below the video picture
56c. At any later time the operator may press the
pushbutton 34c, and the color corrections for scene 0110
will be recalled and applied to the then current scene.
The operator is not required to use the video
pictures on the auxiliary monitor 52 and the pushbuttons 34
to identify the color corrections in any specific order.
For example, the operator could have pressed the button 34d
in order to identify the color corrections for the current
scene. If the operator had done so, the video picture of
the dancer would have been displayed in location 56d instead
of location 56c.
Figure 6C depicts a variation of the video scene
recall feature of the invention. If the operator wishes to
compare the color corrections for two given scenes, the
operator may press the "next to" pushbutton, which is
located in the row of pushbuttons 36 in Figure 4. As an
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1 3 2 6 2 ~ ~ PATENT
333-2052
example, assume that the operator has identified the color
corrections for three scenes as shown by the auxiliary
monitor 52 in Figure 6B and that the operator has pressed
the pushbutton 34b to apply the corresponding color
corrections stored for scene 0097 to the current scene shown
in the lower right hand portion of Figure 6. Now, the
operator desires to compare the effect of the color
- corrections for the current scene, i.e., scene 0115, with
the effect of the color corrections for scene 0097. The
` operator simply presses the "next to" pushbutton. As it is
shown in Figure 6C, the picture of the dog on the main
monitor 50 is then displayed next to the picture for scene
0097 on the auxiliary monitor, and the picture that was in !
location 56c is automatically moved to location 56d.
Consequently, the operator may readily compare the color
corrections for scene 0097 with the color corrections for
scene 0115 on the auxiliary monitor 52. If the operator
wishes to examine the color corrections for these two scenes
on a larger scale, the operator may use the "next to master"
pushbutton, which is shown in Figure 3, thereby causing the
two video pictures to be displayed simultaneously
side-by-side on the master monitor 50.
-~ of course, either video picture can be shown alone
on the master monitor 50. The ability to thus displav a
prior scene or frame on the mastcr monitor 50 without
running the telecine or tape player back saves wear and tear
on the film or tape and minimizes damage due to scratching.
As a further variation, it should be understood
that the identification frames of prior scenes can be
- 23 -
~ 1 3 2 6 2 ~ 3 333-2052
selectively called up from the video memory and displayed on
the master monitor 50 instead cf the auxiliary monitor. The
array of identification frames can be displayed in part of
the screen while the current scene is displayed on the rest
of the screen, or the full array of identification frames
can be displayed by itself, as desired.
The video memory 48 contains sufficient storage
for the twelve video pictures 56 on the auxiliary monitor
52. If the identification of color corrections for more
than twelve scenes is desired, the video memory 48 may
contain additional storage for the additional video
pictures. That is, the video memory 48 may contain
additional pages of memory. In order to move from one page
of the video memory, with an associated display of up to
twelve video pictures on the auxiliary monitor, to another
page of video memory, with a different display of up to
twelve video pictures on the auxiliary monitor, the "page
up" and ~page down" pushbuttons are employed. The "page up"
and "page down" pushbuttons are located in the row of
pushbuttons 36 in Figure 4.
Figure 16 of the drawings is a flowchart
illustrating a computer program used to operate the
"Call-A-Picture" feature of the invention. The routine is
gcnerally designated by the reference numeral 500.
Initially, the routine checks to ascertain
whether the "store" button in the row 36 (Figures 2 and 4)
has been pressed, as indicated at 502. If so, the routine
thcn checks to determine whether a button in the array 34 of
buttons has been pressed, as denoted at 504. However, if
- 24 --
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PATENT
1 32 62 ~ ~ 333-2052
the "store" button in the row 36 has not be~n pressed, the
routine simply inquires whether a button in the array 34
(Figures 2 and ~1 has been actuated, as indicated at 506.
The left branch of the flowchart in Figure 16, starting with
the decision block 504, may be considered as a "write" mode
since video picture information is stored during this mode.
Correspondingly, the right branch of the flowchart in Figure
16, starting with the decision block 506, may be considered
as a "read" mode since video picture information is recalled
during this mode.
Once the "store" button (Figure 4) and a button in
the array 34 (Figure 4) have been pressed, the routine
~4 determines specifically which button in the array 34 was
actuated, as shown at 598. Then, the routine stores the
video signals for the video picture appearing on the main
monitor 50 (Figure 1) in the video memory 48 (Figure 1), as
illustrated at 510. Subsequently, the routine displays a
video picture from the video memory 48 (Figure 1) on the
auxiliary monitor 52 (Figure 1) in the location 56 (Figures
1 and 6) corresponding to the button in the array 34 that
was just actuated, as indicated at 512. In addition, the
routine stores the scene number for the current scene on the
auxiliary monitor 52 in the numerical display directly
beneath the appropriate location 56, as depicted at 514.
Moreover, the routine identifies the color cor-
:- rections for the current scene with a flag corresponding to
the button in the array 34 that was just pressed, as shown
at 516. This flag will be used during the "read" mode in
order to access these color corrections and recall them from
the computer 42 (Figure 1). For example, a button in the
- 25 -
`` I 3262~
PATENT
333-2052
array 34 of buttons may be identified with a flag through
the use of a suitable subroutine. A person having ordinary
skill in the art would understand that various techniques
may be employed to accomplish this tas~. Consequently, such
steps will not be discussed here in detail.
Referring now to the right branch of the routine
illustrated in Figure 16, i.e., the steps used in the "read"
mode, this mode is entered by simply pressing a button in
the array 34 of buttons (Figures 2 and 4), as shown by the
decision block 506. Once this mode has been entered, the
routine determines specifically which button in the array 34
was actuated, as indicated at 518. The routine then reads
the flag corresponding to the button that was just pressed,
as illustrated at 520.
Next, the routine uses the flag to retrieve the
associated color corrections from the computer 42
(Figure l), as depicted at 522. For instance, a suitable
subroutine may be called and utilized to retrieve the color
corrections for the previous scene from the computer 42. A
person having ordinary skill in the art would understand
that various techniques may be employed to accomplish this
task. Accordingly, such steps will not be discussed here in
detail.
After the color corrections for the previous scene
have ~een retrieved from the computer 42 (Figure 1), they
are applied to the uncorrected video signals from the video
signal source 44 (Figure 1), as denoted at 524, to produce
color corrected video signals. These color corrected video
signals are delivered to the main monitor 50 (Figure 1),
which then displays a color corrected picture.
- 26 -
1 326~
PATENT
333-2052
Referring again to th~ right branch of the routine
shown in Figure 16, the blocks below block 524 depict addi-
tional aspects of the "Call-A-Picture" feature of the in-
vention.
Namely, the routine inquires whether the "next to"
button in the xow 36 of buttons (Figure 4) has been pushed.
If not, no further action is taken by the routine. However,
if the "next to" button has been actuated, the routine
storcs the video signals for the video picture appearing on
the main monitor 50 (Figure 1) in the video memory 48
(Figure 1), as designated at 528. The video picture on the
main monitor 50 shows the effects of the recalled color
corrections for the previous scene after they have been
applied with or without modifications to the present scene.
Specifically, the color corrections obtained through the
steps shown by blocks 518, 520, 522, and 524 are applied to
the video picture for the current scene, and then this color
corrected video picture is stored in the video memory 48, as
indicated at 528.
Subsequently, the routine displays the video
picture that was just stored in the video memory 48 on the
auxiliary monitor 52 (Figure 1), as illustrated at 530.
This video picture is displayed in a location 56 (Figures l
and 6) that is adjacent to the location 56 corresponding to
the button in the array 34 that was pressed to enter the
"read" mode. The routine also rearranges the other video
pictures on the auxiliary monitor 52, as shown at 532, if
necessary, in order to properly position the miniaturized
video picture for the present scene.
-
- 27 -
-
3262~g PATENT
333-2052
Blocks 534, 536, and 538 in Figure 16 illustrate
an additional aspect of the "Call-A-Picture" feature of the
invention, Starting with the decision block 534 in the
lower riqht-hand portion of Figure 16, the routine
ascertains whether the "next to master" button in the middle
row 26 of buttons (Figure 3) has been pushed. If not, the
routine takes no further action. However, if the "next to
master" button has been actuated, the routine reads the
video picture information for two video pictures from the
video memory 48 (Figure 1), as indicated at 536. Namely,
the video picture information for the picture that was
stored during the steps designated by block 530 is réad from
the video memory 48, as is the video picture information for
the location 56 corresponding to the button in the array 34
that was pressed to enter the "read~ mode. The retrieved
video picture information is displayed on the main monitor
50 (Figure 1), as shown at 538. Accordingly, the operator
may observe the effe~ts of certain color corrections on both
the present scene and a prior scene, and, as noted
previously, these color corrections may be modified when
they are applied to the present scene. This observation may
be made on the main monitor S0 through the use of the "next
to master" button in order to enable the operator to clearly
view the two video pictures on an enlarged scale.
Figure 17 of the drawings is a flowchart
illustrating another computer program that may be used to
operate the YCall-A-Picture" feature of the invention. The
routine is generally designatod by the reference numeral
600.
- 28 -
:
1 3 2 6 2 ~ ~ 333-2052
Initially, the routine checks to determine whether
the "st9re~ button in row 36 (Figures 2 and 4) has been
pressed, as indicated at 602. If so, the routine then
checks to determine whether a button in the array 34 of
buttons (Figures 2 and 4) has been actuated, as denoted at
604. However, if the ~store" button has not b~en pressed,
the routine just inquires whether a button in the array 34
has been actuated, as indicated at 606. As in the flowchart
of Figure 16, the left branch of the flowchart of Figure 17
may be considered as a "write" mode, while the right branch
of the flowchart may be considered as a "read" mode.
After the "write" mode has been entered by
pressing the "store" button and then by pressing one of the
buttons in the array 34, the routine determines exactly
which button in the array 34 was pressed, as denoted at 608.
The routine next displays the video picture from the main
monitor 50 (Figure 1) in a reduced form on the auxiliary
monitor 52 (Figure 1), as shown at 610. The reduced video
picture is displayed in the Iocation corresponding to the
button in the array 34 that was just actuated. The routine
then stores the present color corrections in a suitable
location in the memory o' the computer 42 (Figure 1), as
illustrated at 612. Specifically, a number of memory
locations in the computer 42 have been allocated for the
miniaturized video pictures that may be displayed on the
auxiliary monitor 52. The storage step shown at 612 causes
the present color corrections to be stored in the memory
location corresponding to the button in the array 34 that
was just pressed. This storage step is the last task
performed in the "write" mode.
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~ ` ~`~; `
1 3 2 6 2 & ~ 333-2052
Referring now to the right branch of the routine
illustrated in Figure 17, i.e., to the steps used in the
"read~ mode, this mode is entered merely by pressing a
button in the array 34 of buttons (Figures 2 and 4), as
shown by the decision block 606. Once this ~ode has been
entered, the routine determines exactly which button in the
array 34 was pressed as denoted at 614.
The routine then inquires whether the "next to"
button in the row 36 (Figure 4) has been pushed, as denoted
at 616. If so, the routine forms a split screen on the
auxiliary monitor 52, as indicated at 618. Subsequently,
the routine checks which of several split screen options has
been selected by the operator and then uses the appropriate
split screen option to divide the display on the auxiliary
monitor 52, as indicated at 620. For example, the screen of
the auxiliary monitor may be divided into left and right
halves, or into top and bottom halves. Additionally, the
screen may be divided into three sections, with one video
picture appearing in the center section and another video
picture appearing in the two sections bordering the center
section. Furthermore, the dividing line between the two
portions of the screen may be positioned as desired by the
operator.
The routine then ascertains whether thc "next to"
button has again bcen pressed, as indicated at decision
block 622. If not, the routinc repeats the steps in blocks
618 and 620. If the "next to" button has again been
pressed, the routine restores the normal twelve-picture
display on the auxiliary monitor 52, as shown at 624.
- 30 -
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~ 1 3 2 6 2 ~ ~ PATENT
Referring to the right branch of the flowchart of
Figure 17, if the routine is in the "read" mode and the
"next to~ button has not been actuated, the routine inquires
whether the ~A" button or the "B" button or the "picture
file" button in the upper row of buttons 24 (Figure 4) has
been pressed, as indicated by the decision blocks 626, 634,
and 642.
When the "A" button is actuated during the "read"
mode, the routine changes the pointer associated with the
"A" buffer, as designated at 628. That is, the routine
causes the pointer for the "A" buffer to assume a value
corresponding to the memory location in the computer 42
associated with the button in the array 34 that was pressed
to enter the "read" mode. Then, the routine uses the
pointer to read the appropriate color corrections from the
computer 42, as illustrated at 630. The routine next
applies these recalled color corrections to the uncorrected
video signals from the video signal source 44, as indicated
at 632, to produce color corrected video signals, which are
displayed on the main monitor 50.
If the "A" button has not been pressed during the
"read" mode, the routine inquires whether the "B" button has
been pressed, as denoted at 634. If so, the routine carries
out substantially the same steps as shown in the blocks 628,
:,
. 630, and 632, in the blocks 636, 638, and 640.
r'~. If the "A" button and the "B" button have not been
pressed during the "rcad" mode, the routine determines
whether the "picture file" button in the upper row of
buttons 24 (Figure 4) has been actuated. ~his step is
illustrated by the decision block 642. The purpose of the
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1 3262~,3 PATENT
333-2052
"picture file" button is to cause the selected miniature
video picture in the twelve-picture display to be displayed
over the entire area of the au~iliary monitor. Accordingly,
when the "picture file" button has been pressed during the
~read" mode, the routine changes the pointer for the
npicture file" buffer, as designated at 644. The steps used
to carry out the function denoted at block 644 are
essentially the same as the steps used to carry out the
functions denoted at the blocks 628 and 636. After the
pointer has been changed, the routine uses the pointer to
read the appropriate color corrections from the computer 42,
as shown at 646. These retrieved color corrections are then
applied to the uncorrected video signals from the video
signal source 44, as indicated at 648, to produce color
corrected video signals, which are displa~ed on the main
monitor 50. Additionally, the routine displays the video
picture associated with the button in the array 34 that was
pressed to enter the "read" mode over the entire area of the
auxiliary monitor 52, as illustrated at 650. In other
words, the auxiliary monitor 52 shows the selected video
picture on an enlarged scale, i.e., on a scale like that of
the main ~onitor 50.
If neither the "A" button nor the "B" button nor
the "picture file" button has been pressed during the "read"
mode, the routine inquires whether the equipment is in the
nnext to" mode, as indicated at 652. The ~next to~ mode is
entered by once pressing the "next to" button. If so, the
routine again checks which of several split screen options
~-
has been selected by the operator and then uses the
appropriate split screen option to divide or redivide the
.
- 32 -
: `
1 3262~ PATENT
333-2052
display on the auxiliary monitor 52. This step is
designated at 620.
The "next to" button as described above in
connection with the flowchart of Figure 17 permits the
operator to compare two full-size video picture~
simultaneously on the auxiliary monitor. This i8
accomplished with a split screen. One video picture was
previously stored and is now being recalled, while the other
video pictuxe is identical to the video picture on the main
monitor. However, the video signals used to produce the
latter video picture are subjected to essentially the same
type of signal processing as the video signals used to
produce the former video picture. In other words, the video
signals producing the picture on the main monitor are
initially converted into digital signals and subsequently
converted back to analog signals. This signal processin~
J
technique results in pictures on the auxiliary monitor that
are affected in the same way by the digitizing process.
. . .
Thus, the operator is better able to observe the effects of
certain color corrections on the present scene as compared
to the prior scene. Furthermore, the use of two full-size
video pictures permits the operator to better match the
telecine position and/or size adjustments for the present
scene with the prior scene.
The switching between the two video pictures on
the auxiliary monitor may be accomplished while the signals
are in their digital form. Consequently, differential
distortions arising from conventional analog switching
circuits, e.g., wiping circuits, are eliminated.
- 33 -
1 3262~ 333-2052
The video picture ~torage technique dcscribed
above in connection with Fiqure 17, l.e., the technique in
which specific memory locations in the computer 42 are
allocated for color correct~ons associated with the
miniature video pictures on the auxiliary di~play, may be
thought of as "video scratch-pad memory. n That ~6, the
color corrections stored in the allocated memory locations
are not necessarily related to color correction events.
These color corrections may be accessed at random, with the
miniature video pictures on the auxiliary display beinq
useful to remind the operator of what these color
corrections relate to. This feature permits the operator,
on a random basis, to store and recall color corrections
that were originally created on a temporary basis.
Color Correction Circuit Block Diagram
Figures 7A and 7B together comprise a block
diagram for the color correction circuit of the color
corrector 11.
The componcnts 130 through 176 and their
interconnections, all shown in Figure 7A, are described in
detail in Patent No. 4,750,050 and that description will not
be repeated in detail here.
Refer~ing now to Figure 7~, the serial receiver
180 and the digital logic circuits 182 scrve the samc
functions as described in Patent No. 4,750,050
but are modified to receivc control signals for the variable
vector control circuits 184 as well as csntrol s~gnals for
the variable vector matte generator 186 and the six vector
'
- 34 -
~J
~ .
.,, :
PATENS
1 3 2 6 2 8 8 333-205?
;m~tte gen~r~tor 188. ~he v~r~ble vector control ~rcu~t~
18~ ar~ de~crib~d 1~ gre~ter det~11 below in connectio~ wlth
~lgures 8 snd 9. The clrcult~ for the v~r~bl~ v~ctor matte
generator 186 and the alx vector matte gener~tor 188 are
shown and described in Patents Nos. 4,679,067 and 4,694,329.
Specifically, four programmable counters may be employed for
each of the matte generators 186 and 188. The counting
information for each of thc programmable counters is
supplied by the computer 42 over the coaxial cable 178 to
the serial receiver 180. The serial receiver then delivers
corresponding signals to the matte generator circuits 186
and 188.
;..
:In Figure 7B, the saturation multibank assembly
.,
164 is the circuitry operated by the six control knobs in
the top row of ~nobs on the panel 16 ln Fig~re 2.
S$milarly, the hue multibank assembly 166 iS controlled by
the six knobs ln the middle row, and thc lum~nance multibank
assembly 168 ls controlled by the six knobs in the bottom
row of the panel 16. As it is well known, each of the
eighteen knobs in the panel controls a parameter for colors
wlthin a fixed sector of the color circle represented on a
vector~cope screen.
The correction summation circuit 170 sums the
signa's it receives and produces correction sign21s for the
red ~nRn), blue ~B~), and green (~Gn) signals, while the
luminance summation circuit 172 similarly generates a
correction signal for the luminance InYn) signal, ~s
described in Patent No. 4,750,050. The magnitudes of the
correction signals depend upon the levels of the D.C.
'rW
;
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l 3262g~
PATENT
333-2052
signals received from the serial receiver 180. Similarly,
the variable vector control circuits 184 provide correction
signals for the R, B, G, and Y signals. ~he variable vector
control circuits receive D.C. signals from the serial
receiver 180. The magnitudes of the correction signals for
the R, ~, G, and Y signals depend upon the levels of the
associated D.C. signals. The correction signals are
identified as the +R, +B, +G, and +Y signals in Figures 7A
and 7B.
The correction signals from the variable vector
control circuits 184 are added to the correction signals
from the correction summation circuit 170 and the luminance
summation circuit 172 at points 194, 196, 198, and 200. The
added correction siqnals are delivered to the combiner 160
~Pigure 7A), where they are combined with the R, B, G, and Y
signals from the processors 142-148 to produce color
corrected R, B, and G signals. The color corrected R, B,
and G signals are sent from the combiner 160 to an encoder
176, which produces a color corrected composite video
signal. The color corrected composite video signal is sent
to the main monitor 50 and the video tape recorder 46, as
shown in Figure 1.
The variable vector control circuits 184 output a
variable vector signal when the vector determined by the R,
B, and G signals at the input is within the range set by the
variable vector controls. The variable vector signal is
sent over a line 190 to an AND ~ate 192 (Figure 7A). The
other input to the AND gate 192 is a variable vector "set
up" signal from the "set up" pushbutton 92 on the front
panel 12. When the "set up~ pushbutton is pressed and the
- 36 -
1 3262~8 PATENT
- 333-2052
variable vector signal is preSent, the output of the AND
gate 192 becomes HIGH and actuates a switching circuit 202.
The switching circuit 202 shorts together the R, B, and G
output signals from the combiner 160. Accordingly, a
neutral gray is produced as the composite video output of
the encoder 176. As a result, the operator may observe on
the main monitor 50 which colors are within the range 8et by
the variable vector controls. If the colors the operator
wants to correct are not within this range, the operator may
adjust the variable vector position control 80, the delta
control 82, and~or the factor control 84, as discussed
previously.
The control knobs are each connected to a circuit
that provides a numerical value indicative of the amount of
rotation of the knob. It should be understood that this
circuit which determines the amount of rotation of one of
.;~
the control ~nobs 86, 88, and 90 is automatically reset to
zero after each storage of its settings. This operation
~zeros" the knobs in preparation for further corrections.
Traveling Matte Feature
The correction signals from the variable vcctor
control circuits 184, the correction summation circuit 170,
and the luminance summation circuit 172 may be and normally
are applied to the video picture signals for the entire
picture. Moreover, by the use of the "traveling "mattc"
feature of the invention, the correction signals from the
variable vector control circuits 184 may be applied to the
video signals in a predetermined area of the video picture
which is smaller than the area of the entire picture.
Similarly, the correction signals from the correction
1 3262~ PATENT
333-2052
summation circuit 170 and the luminance summation circuit
172 may be applied to another predetermined area of the
video picture which is smaller than the area of the entire
picture.
When the operator desires to apply the correction
signals from the variable vector control circuits 184 to the
video picture signals in only a limited area of the picture,
the operator presses the "variable vector matte on"
pushbutton (Figure 3) on the front panel 12, which produces
a variable vector matte enable signal on a line 204 (Figure
7B). The variable vector matte enable signal on the line
204 is delivered to one input of an AND gate 206. The other
input of the AND gate 206 is supplied by the variable vector
matte generator 186 through a switching circuit 208.
Consequently, the output of the variable vector matte
generator 186 determines whether the output of the AND gate
206 is HIGH or LOW. If output of the AND gate 206 is HIGH,
the switches in a switching circuit 210 all are closed, but
if the output of the AND gate 206 is LOW, the switches are
open. The switching circuit 210 permits the correction
signals from the variable vector control circuits 184 to
travel to the combiner 160 ~Figure 7A) only when the output
of the AND gate 206 is HIGH. The variable vector matte
generator 186 may be programmed to supply a HIGH signal to
the input of the AND gate 206 either inside of the
associated predetermined area or outside of the associated
predetermined area. Therefore, the correction signals from
the variable vector control circuits 184 may be applied to
the video picture signals either inside of or outside of the
specified area.
- 38 -
~ 1 3262~ PATENT
333-2052
When the operator desires to apply the correction
signals from the correction summation circuit 170 and the
luminance summation circuit 172 to the video picture signals
in only a limited area of the picture, the operator presses
the "six vector matte on" pushbutton (Figure 3) on the front
panel 12, which produces a six vector matte enable signal on
a line 212 (Figure 7B). The six vector matte enable signal
on the line 212 is delivered to one input of an AND gate
214. The other input of the AND gate 214 is provided by the
six vector matte generator 188 through a switching circuit
216. Consequently, the output of the six vector matte
generator 188 determines whether the output of the AND gate
214 is HIGH or LOW. If the output of the AND gate 214 is
HIGH, the switches in a switching circuit 218 are closed,
but if the output of the AND gate 214 is LOW, the switches
in circuit 218 are open. The switching circuit 218 permits
the correction signals from the correction summation circuit
170 and the luminance summation circuit 172 to travel to the
combiner 160 only when the output of the AND gate 214 is
HIGH. The six vector matte generator 188 may be programmed
to supply a HIGH signal to the input of the AND gate 214
either inside of or outside of the associated predetermined
area. Thus, the correction signals from the correction
summation circuit 170 and the luminance summation circuit
172 may be applied to the video picture signals either
inside of or outside of the specified area.
An external matte generator, such as a special
effects generator, may bc used to detcrmine the window for
the correction signals from the variable vector control
circuits 184 and/or the window for the correction signals
- 39 -
: 1 3 2 6 2 8 ~ 333-2052
from the correction summation circuit 170 and the luminance
summation circuit 172. The external matte generator
produces an external matte signal, which is delivered to
each of the switching circuits 208 and 216. The external
matte signal is enabled by the ~matte external~ pushbutton
(Figure 3) on the front panel 12. The operator controls the
i,
state of the switching circuits 208 and 216 so that the
external matte generator supplies a signal to the AND gate
206 and/or the AND gate 214. Thus, the external matte
generator may determine a limited area of the picture to be
;
color corrected.
As an example of the foregoing, Figure 1 shows the
outlines of two windows, window Wl and window W2. The
correction signals from the variable vector control circuits
184 may ~e applied to the video picture signals either
inside of or outside of the window Wl. Correspondingly,
the correction signals from the correction summation circuit
170 and the luminance summation circuit 172 may be applied
to the video picture signals either inside of or outside of
the window W2.
The size and/or the position of each of the
windows W1 and W2 may be changed by the operator by using
the window controls 20 (Figure 2) on the front panel 12.
The window controls 20 are described in detail in
application Serial No. 598,468 and application Serial No.
722,801. The windows W1 and W2 may overlap, as depicted in
Figure 1.
Signals that determine the size and the position
of the windows W1 and W2 may be stored in the computer 42
for each scene or frame, just as signals for determining the
- 40 -
~ ' , '~
, .
r~~
1 32628~ PATENT
333-2052
color corrections are stored in the computer 42 for each
scene or frame. For instance, if each matte generator
includes four programmable counters, the count information
for each counter may be stored for each scene or frame.
The operator employs the window controls 20 to
determine the size and the position of a window. Once the
desired window is obtained, the operator presses the "matte
store" pushbutton (Figure 3) and signals indicative of the
size and the position of the window are stored in the
computer. The window may be altered for each new scene or
frame, if necessary. Accordingly, a window may be placed
around an object in a particular scene or frame and color
corrections applied within the window using, for example,
the variable vector controls. In subsequent scenes or
frames, the size and/or the position of the window may be
changed to follow the object. Thus, a window may "travel
with" the object from scene to scene or from frame to frame.
This feature of the invention allows greater object
selectivity and improves the quality of the final color
corrected videotape. Furthermore, this feature of the
invention in combination with the variable vector controls
permits even greater object selectivity and further improves
the quality of the final color corrected videotape.
Normally, a single window location can be used for
many different successive frames despite movement by the
object to be segregated from the remainder of each picture
frame. This can be accomplished by simply making the window
size and shape such that it will enclose the object at all
times during each succcssive frame. Then, when the movement
of the object takes it outside of the window boundaries, a
'
- 41 -
, ,
1 32~2~ PATENT
333 2052
new window can be formed and stored for the frame where this
- occurs, an~ for subsequent frames.
Of course, if the location of the boundaries of
the window must be very close to the object, a new window
can be constructed and stored for each frame or every other
. ~
frame, etc. during a particular frame sequence.
In accordance with another feature of the
invention, the boundaries of the window are made "soft" so
as to cause the color corrections made in the segregated
.
area to blend in with the adjacent areas as smoothly as
possible. This makes it possible to apply a color
correction in a specific portion of a relatively large
colored area and blend the corrected and uncorrected areas
together smoothly. For example, it is possible to form a
window in the middle of a cheek of a person's face and add
some red in the window to make the person's cheek look
rosier. The edges of the rosy area are blended smoothly
with the other portions of the chee~ to give the cheek a
natural rosy appearance.
The "soft" edges o the window are formed by
forming two windows, one inside the other and spaced apart
by a predetermined distance, and by performing a linear
dissolve between the signals at the two window boundaries.
The computer may be programmed to provide a smooth
transition between the window in one scene and the window in
another scene. This may be accomplished in much the same
manner as the "dissolve" pushbutton is employed to produce a
smooth transition between the color corrections in one scene
and the color corrections in the following scene. More
particularly, each window boundary may be changed on a
,'
- 42 -
,f-i
1 3262~3 PATENT
333-2052
frame-by-frame basis starting at a frame near the end of one
scene and ending at a frame near the beginning of the
subsequent scene.
with this travelling matte feature, the precise
outlines of an object to be color corrected do not have to
be defined in order for color corrections to occur over the
selected hue or hues. All that is necessary is that the
matte is positioned to include the object to be corrected
and exclude objects whose colors are to remain unchanged.
Block Diagrams for the Variable Vector Control Circuits
Figures 8 and 9 are block diagrams for the vari-
able vector control circuits 184 of Figure 7. In Figure 8,
red ("R"), green (nG"), and ~lue (nB") signals from the
decoder enter a luminance matrix 230 and produce a luminance
signal ( lly~ ) at the output of the luminance matrix.
An R-Y signal is one input of a four-quadrant
multiplier 232. A B-Y signal is one input of a
four-quadrant multiplier 234. The R-Y and B-Y signals are
in quadrature. Accordingly, any vector may be selected by
taking appropriate portions of the R-Y and B-Y signals. The
sin~ and cos~ signals from the coefficient processor (shown
in detail in Figure 9) are used to select the appropriate
portions of the R-Y and B-Y signals. Other signals which
are in quadrature, such as the I and Q signals, may be
employed, however. The sin~ signal is delivered to the
other input of the four-quadrant multiplier 232, while the
cos~ signal is supplied to the other input of the
four-quadrant multiplier 234. The output signals from the
four-quadrant multipliers 232 and 234 determine the
- 43 -
1 3262~
PATENT
333-2052
principal color in the range of colors set by the variable
vector position control.
The range around this principal color is, however,
relatively large. Consequently, the four-quadrant
multipliers 238, 240, and 242 are employed to narrow the
range. The R-Y signal is one input of the four-quadrant
multiplier 238, and the B-Y signal is one input of the
four-quadrant multiplier 240. A Dcos~ signal is the other
input of the four-quadrant multiplier 238, and a Dsin~
signal is the other input of the four-quadrant multiplier
240. The Dcos~ signal is like the cos~ signal except that
the amplitude is changed by the value D. Similarly, the
Dsin~ signal is like the sin~ signal except that the
amplitude is changed by the value D. The output signals
from the four-quadrant multipliers 238 and 240 determine a
vector which is in quadrature with the vector determined by
the output signals from the four-quadrant multipliers 232
and 234.
The vector determined by the output signals from
the four-quadrant multipliers 238 and 240 is squared by a
four-quadrant multiplier 242 in order to eliminate any
negative portions of it. The difference between the output
signal from the four-quadrant multiplier 242 and a reference
signal is one input of a four-quadrant multiplier 236. The
other input of the four-quadrant multiplier 236 is the
difference between the output signals from the four-quadrant
multipliers 232 and 234. Consequently, the output signal
from the four-quadrant multiplier 242 modifies the vector
determined by the output signals from the four-quadrant
multipliers 232 and 234. In particular, the output signal
- 44 -
1 3 2 6 2 ~ ~ PATE~T
- 333-2052
; from the four-quadrant multiplier 242 narrows the range
around the principal color. The value D determines the
width of the range around the principal color. By changing
the value D, the magnitude of the output signal from the
four-quadrant multiplier 242 is changed, and a larger or
smaller amount i8 subtracted from the reference signal at
the input of the four-quadrant multiplier 236. An
explanation of how the value D is obtained is included below
during the description of the coefficient processor.
The output signal from the four-quadrant
multiplier 236 is sent to a level discrimination circuit
244. The level discrimination circuit 244 is shown in
Figure 10 and described in greater detail below. In short,
the level discrimination circuit 244 discriminates signals
above a first preset level from signals below the first
preset level, and it discriminates signals above a second
preset level from signals below the second preset level.
Signals above the first preset level are supplied over a
line 248 to each of the four-quadrant multipliers 252, 254,
256, and 258. Furthermore, signals above the second preset
level are delivered over a line 250 to each of the four-
quadrant multipliers 252, 254, 256, and 258.
- The difference between the signal on the line 248
and the signal on the line 250 is used as one input of each
of the four-quadrant multipliers 252, 254, 256, and 258.
The other input of each of the four-quadrant ~ultipliers
252, 254, and 256 is provided by the coefficient processor,
while the other input of the four-quadrant multiplier 258 is
supplied by the serial receiver 180 lFigure 7~). The
coefficient processor delivers signals identified as 0,
1 326~3 PATENT
333-2052
120, and 240. These ~iqnals resolve the variable vector
signal into components correspondi~g to the R, G, and B
signals. The signal from the serial receiver is a luminance
correction signal, which corresponds to the position of the
variable vector luminance control 90 ~Figure 2) on the front
panel 12. This correction signal produces a luminance
correction ("+Y") at the output of the four-quadrant
multiplier 258. The luminance correction is delivered to
the combiner 160 (Figure 7A).
Figure 8 depicts an alternative location for the
circuit which controls the variable vector window. Namely,
a switching circuit 246 is located between the level
discrimination circuit 244 and the four-quadrant multipliers
252-258. The switching circuit 246 receives a variable
vector matte control signal, such as the output signal from
the AND gate 206 (Figure 7B), which controls whether the +R,
+G, +B, and +Y correction signals will be supplied to the
combiner 160 (Figure 7A). When the switches in the
switching circuit 246 are in the position shown in Figure 8,
the correction signals will be sent to the combiner 160;
when the switches are in the other position, the output
signals from the discrimination circuit 244 on the lines 248
and 250 are grounded. Consequently, no +R, +G, ~B, and +Y
signals are developed at the outputs of the four-quadrant
multipliers 252-258 and no such correction signals are
provided to the combiner 160 when the switching circuit 246
is in its other position. Thus, the variable vector matte
control signal enables and disables the variable vector
control circuit at the boundaries of the window.
- 46 -
1 3 2 6 ~ ~ ~ 333-2052
The right-hand portion of Fi~ure 8 illustrates a
wideband differential amplifier 259, which is connected to
the output lines of the level discrimination circuit 244 and
the switching circuit 246. The amplifier 259 provides the
variable vector signal in its output line 190. The variable
vector signal is mentioned above during the description of
Figures 7A and 7B.
As it can be seen from the foregoing description,
the circuitry shown in the left-hand portion of Figure 8 is
a versatile, accurate video color detector. Although the
foregoing description is adequate, the following
supplemental discussion should help in understanding it in
even greater depth.
Figure 12 of the accompanying drawings is a
schematic vector representation of the hue and saturation of
a given color video signal, as it is shown on the familiar
"vectorscope" used in video production equipment. The angle
"~" of the vector represents the hue or color of the
signals, and the length "S" of the vector represents the
saturation or intensity of the signals.
The color detector circuit of Figure 8 makes it
possible to rotate the vector ~S" through an angle of 360
or more so as to select almost any hue as the principal
color to be detected. The hue selection control is
essentially infinitely variable.
The details of the manner in which the foregoing
is accomplished can be explained with the further assistance
of Figure 13.
Figure 13 is an enlarged and more detailed view of
the multiplier circuit 232 shown in Figure 8. The circuit
- 47 -
1 326288
PATENT
333-2052
232 is an integrated circuit including a pair of
differential amplifiers 441 and 443 which deliver their
outputs to an analog multiplier circuit 445, which delivers
to an amplifier 447 a signal proportional to the product of
its two input signal~ X and Z. Amplifier 447 delivers an
amplified signal proportional to the product (X)(Z) on one
output line 451, and an inverted signal proportional to the
product (X~(ZI on another output line 449.
One satisfactory integrated circuit chip for this
use is the MC1595L multiplier sold by Motorola, Inc.
Thus, the input signal (R-Y) is formed by the
differential amplifier 441, which has (R) applied to its ~+)
input terminal and ~Y) to its (-) terminalO
Each multiplier circuit shown in Figure 8, that
is, each of the multipliers 232, 234, 236, 238, 240, 242,
252, 254, 256, and 258, has the same structure as the
multiplier 232 shown in Figure 13.
Referring again to Figure 8, in a similar manner,
the (B-Y) signal is formed as one input to the four-quadrant
multiplier circuit 234. As is shown in Figure 12, the ~R-Y)
and (B-Y) signals are defined to be in quadrature. The
vector "S" of Figure 12 is the resultant of the (R-Y) and
(B-Y) vector signals. The angle ~ formed by the vector "S"
is the measure of the hue of the video signals.
As it has been noted above, the angle ~
corresponding to the hue to be detected by the color
detector of Figure 8 can be selected at any angle from 0 to
360. This is accomplished, in effect, by the use of a
variable, selectable passband filter circuit which filters
out all signals other than those within a certain passband
- 48 -
1 3 2 6 2 8 8 333-2052
around the selected hue corresponding to the angle ~. Thus,
the signal (sin ~) is supplied as a second input to the
multiplier 232, and the signal (cos a) is supplied as a
second input to the multiplier 234. The output of
multiplier 232 is proportional to (R-Y)sin ~, and that from
multiplier 234 is propor~ional to (B-Y)cos ~.
The outputs from multipliers 232 and 234 are
delivered to the (+) and (-) input terminals, respectively,
of the multiplier circuit 236 so as to form the input signal
[(R-Y)cin ~ - (B-Y)cos ~.
Although the resultant color vector detected can
be rotated through an angle of 360 or more by varying ~,
the operation of the circuit described so far as a color
detector is unsatisfactory because the range of hues it
recognizes is so broad that it tends to recognize colors
substantially different from the principal color.
The latter problem is illustrated in Figure 14 in
which the curve 412 expresses the relationship between hue
and the output of the multiplier circuit 236 due solely to
the input signals described so far; that is, without
consideration of the signals applied to the lower pair of
terminals of the multiplier circuit 236. The curve 412 is
relatively broad and crosses the zero-axis at two points,
one of which leads ~ by 90, and one of which lags 0 by 90;
that is, the curve 412 covers an area spanning 180 of the
color spectrum. A second curve is shown at 416. This curve
results from a shift of the angle ~ to a new value ~'.
In prior art color detectors, a level detector
circuit is used to discriminAte against all signals lower in
magnitude than a preset level 414. By this means, the range
- 49 -
1 3 2 6 2 8 8 PATENT
; 333-2052
of hues detected by the circuit is narrowed to the area
between points A and B, where the preset level ~14 crosses
the curve 412, without affecting the passband of the
detector circuit itself. Because the shape of the curve 412
remains very broad, usually the range of hues between points
A and ~ also is relatively broad. Furthermore, the~shape of
the curve 412 makes the detector circuit largely dependent
on saturation levels rather than hue.
In accordance with a valuable feature of the
invention, the passband of the hue selector circuit itself
~ is narrowed by the use of the detector circuit shown in
; Figure 8.
With this feature, the passband can be made as
narrow as 2 and as broad as 90 on either ~ide of the
center, or principal color, substantially independently of
the saturation of the input signals.
Multiplier 238 develops a signal of (R-Y) on its
upper terminals. A signal ~Dcos e) is developed on its
lower terminals by the circuit shown in Figure 9 which
multiplies the cos ~ signal by a "delta" factor "D. n
Similarly, (B-Y) and (Dsin ~) signals are
developed at the input terminals of the multiplier 240.
: The outputs from multipliers 238 and 240 are
subtracted from one another by the input differential
amplifiers in the multiplier circuit 242 which, as noted
-~ abovc, is used as a squarer. Thus, the quantity
l(R-Y)(Dcos ~) - (B-Y)(Dsin 0)] is formed at the output of
each input differential amplifier (441 and 443 in Figure 13)
of thc circuit 242. Those signals are multiplied by one
- 50 -
1 326288 PATENT
333-2052
another ~multiplier 445 in Figure 13) to square that
quantity and produce a signal N:
N = l(R-Y)(Dcos B) - (B-Y)(Dsin ~)]
at the output of the squarer 242.
This signal N is sent to the lower negative input
terminal of multiplier 236 where it is subtracted from the
reference signal "REFERE~CE." The resulting signal (l-N) is
multiplied with M = [(R-Y)sin ~ - (s-Y)cos ~] and that
product is sent to the level discrimination circuit 244.
The effects of this signal processing are shown in
Figures 15A-15D, which are diagrams illustrating the
operation of the circuitry. The angle ~ or hue is plotted
horizontally against the D.C. output voltage in response to
the successive receipt of numerous signals of equal
magnitude but whose hues vary throughout the visible
spectrum when a specific center hue ~ has been selected for
the passband of the circuit.
Figure 15A shows the variation of the signal ~ =
[(R-Y)sin ~ - (B-Y)cos ~] which is developed at one input of
the multiplier 236. It is a sine wave whose period
represents 360 of the color vector circle, with the
selected hue located at ~, the positive peak of the sine
wave.
Figure 15B shows the output of the squarer 242.
It is 90 out of phase with the wave shown in Figure 15A.
The purpose of squaring the wave at the input of the squarer
242 is to make all peaks of the wave positive. Figure 15B
basically is made up of positive loops, which have a sine2
form.
- 51 -
., , , :
1 3 2 6 ~ 8 8 PATENT
333-2052
- Figure 15C shows the result of subtracting the
signal N shown in Figure 15B from the reference signal. The
reference signal is a D.C. level which preferably is
selected to produce a multiplication of one when N = 0. The
waveform in Figure 15C has positive-going spikes 408 formed
by the cusps between the inverted sine loops formed by the
subtraction process.
The effects on the waveforms of a large delta
factor "D" and medium and small delta factors are indicated,
respectively, by dashed-line curve 410, solid curve 409, and
dashed-line curve 407 in Figure 15C.
The waveform resulting ~rom multiplying signal M
- (Figure 15Ai by the signal shown in Figure 15C is shown in
solid lines in Figure 15D. The negative-going portion of
the waveform between the first and third half-cycles is
eliminated by a negative signal clipper in the level
discriminator circuit 244, so that only positive peaks
remain.
; The waveforms in Figure l5D also express the
transmission characteristics for input signals of variable
hue. That is, signals having a phase angle equal to B, the
selected phase angle defining the desired hue, are
transmitted with maximum values; other signals are
attenuated to a degree depending upon the shape of the
transmission curve, which depends on the delta "D" factor
and the number of degrees that the signal is distant from ~.
It can be seen in Figure 15D that, as the delta
factor "D" is increased, the passband ~ 1 of the circuit
decreases. With a large "D" factor, the passband ~ 1 is
relatively small. B is the center frequency or hue of all
- 52 -
`
1 326288 PATENT
- 333-2052
of the passbands. The passband A2 formed by the use of a
medium "D" factor is wider, thus providing for the detection
of a wider range of hues around the center hue at 0.
Finally, the passband ~3 formed by a small "D~ factor is
very wide, almost 180.
Figures 15A, 15B, and 15D show the waveforms
resulting from a change of the selected hue from ~ to ~'.
The waveform for ~ has been omitted from Figure 15C to avoid
cluttering the drawing, and the waveform for ~' in Figure
l5D has been separated from the waveform for ~ more than it
actually would be for the sake of clarity in the drawings.
It can be seen that the change of the selected hue
from ~ to ~' merely shifts the waveforms to the right in
Figures 15A - 15D. This changes the selected hue from near
red to a hue around magenta. If the knob 80 (Figure 2) is
turned in the opposite direction by the same amount as it
was turned to created the change from ~ to ~', shifting the
vector "S" counterclockwise from the reference burst axis
(see Figure 12), then the waveforms shift to the left by a
corresponding amount to select a color between green and
cyan. The angle ~ can be changed in very small steps or
increments, thus making the hue selection essentially
infinitely variable.
The amplitude of the signal transmitted to the
level discrimination circuit 244 is proportional to the
saturation of the color being detected. The level
discriminator circuit 244 is capable of rejecting all
signals whose saturation falls either above or below a
preset level such as levels 411 and 413 shown in the
right-hand portion of Figure 15D.
- 53 -
1 32 2 8 PATENT
6 8 333-2052
~ y setting the discrimination circuit 244 to pass only
those signals whose saturation is below a certain level, the
device 244 detects and differentiates low-saturation signals
from high-saturation signals of the same hue.
Quite significantly, low-saturation colors can be
detected without any significant degradation of selectivity
in color detection. If preferred for a particular job,
high-saturation colors also can be detected for color
correction, and the saturation selection process avoids the
possibility of developing a detection signal in response to
the detection of a signal of the same hue but lower
saturation.
By permitting the passband to thus be variable in
both phase angle and width, the detector circuit can be
adjusted to select virtually any hue, any one of a number of
different saturation levels, and a passband width so as to
adjust the detector to compensate for varying conditions,
and to eliminate or alleviate many of the problems mentioned
above with prior color detection devices.
Figure 9 is a block diagram of the coefficient
processor. The delta control signal, the variable vector
saturation control signal, the variable vector hue c~ntrol
siqnal, and the variable vector position control signal are
supplied to the coefficient processor by the serial receiver
180. Each signal corresponds to the position of the
associated control on the front panel 12, or an associated
signal from the memory in the computer. Specifically,
variable vector position control signal corresponds to the
position of the variable vector position control 80; the
delta control signal corresponds to the position of the
- 54 -
.. . .
-
1 3 2 6 2 8 8 PATENT
delta control 825 the variable vector saturation control
signal corresponds to the position of the saturation control
86; and the variable vector hue control signal corresponds
to the position of the hue control 88. These signals are
employed with the circuits shown in Figure 9 to produce the
sin~, cos~, Dcos~, Dsin6, 0, 120, and 240 D.C. output
signals from the coefficient processor.
The coefficient processor includes a square wave
generator 260, which produces a 2-MHz square wave signal.
The 2-MHz signal from the square wave generator 260 is sent
to a divide-by-four circuit 262. The output of the
divide-by-four circuit 262 is sent to another divide-by-
four circuit 264 and to a fundamental frequency filter 266.
The output signal from the divide-by-four circuit 264 is de-
livered to a one-shot circuit 268, which triggers a ramp
generator 270. The output signal from the fundamental
frequency filter 266 is a 500-KHz sine wave, while the
output signal from the ramp generator is a ramp. The ramp
extends for four cycles of the 500-~Hz sine wave.
In order to develop the sin~ and cos~ signals, the
variable vector position control signal is compared to two
different reference signals at the comparators 272 and 274.
The variable vector position control signal is delivered to
the minus input of each of the comparators 272 and 274. The
plus inputs of the comparators 272 and 274 are supplied by
the summation circuits 276 and 278, respectively. The
summation circuit 276 adds the ramp signal to a reference
signal, while the summation circuit 278 adds the ramp signal
to a different reference signal. The two different
refcrence signals are selected to correspond to a difference
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8 PATENT
1 32 628 333-2052
of 90 degrees along ~he 500-KHz ~ine wave. Accordingly, the
output signals from the comparators 272 and 274 change from
positive to negative at points 90 degrees apart along the
sine wave produced ~y the fundamental frequency filter 266.
The output signals irom the comparators 272 and
274 trigger the one-shot circuits 280 and 282, respectively.
The one-shot circuits 280 and 282, in turn, trigger the
sample-and-hold circuits 284 and 286, respec~ively. The
sample-and-hold circuits 284 and 286 sample the 500-KHz sine
wave from the fundamental frequency filter 266. Because the
reference signals at the summation circuits 276 and 278 were
set to correspond to a 90-degree difference, the sample-
and-hold circuits 284 and 286 sample the 500-KHz sine wave
at points which are 90 degrees apart. As a result, the
sample-and-hold circuits 284 and 286 output signals which
have a phase dif'erence of 90 degrees, and these D.C.
signals are referred to as sin~ and cos~.
The variable vector position control signal
determines when the outputs of the comparators 272 and 274
change from positive to negative. Consequently, the
variable position control signal determines the sina and
cos6 signals, and thercby sets the principal color in the
range of colors selected by the variable vector controls.
The sample-and-hold circuits 288 and 290 operate
similarly to the sample-and-hold circuits 284 and 286 in
order to determine the Dcos~ and Dsin~ signals. However,
the sample-and-hold circuits 288 and 290 do not sample the
500-KHz sine wave from the output of the fundamental
frequency filter 266. Rather, the sample-and-hold circuits
288 and 290 sample thc output signal from a multiplier 292.
~i
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~ 326288 PATENT
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One input of the multiplier 292 is the 500-XHz sine wave
from the fundamental frequency filter 266, while the other
input of the multiplier 292 is the delta control signal.
Accordingly, the output signal from the multiplier 292 is a
500-~Hz sine wave which has its amplitude modified by the
delta control siqnal.
When the one-shot circuits 280 and 282 trigger the
sample-and-hold circuits 284 and 286, the one-shot circuits
280 and 282 simultaneously trigger the sample-and-hold
circuits 288 and 290. Thus, the sample-an~-hold circuits
288 and 290 sample a 500-KHz sine wave whose amplitude has
been modified by the delta control signal to produce the
Dcos~ and Dsin~ signals, respectively. The delta control
signal, therefore, determines the value D, which sets the
width of the range of colors around the principal color.
The comparators 294-298, the summation circuits
300-304, the one-shot circuits 306-310, and the
sample-and-hold circuits 312-316 operate like the circuits
described above to produce the 0, 120, and 240 output
signals. However, the sample-and-hold circuits 312-316 do
not sample the 500-KHz sine wave from the output of the
fundamental frequency filter 266. Instead, the
sample-and-hol* circuits 312-316 sample the output of the
multiplier 318, which is also a 500-KHz sine wave. The 500-
KHz sine wave output of the multiplier 318 is derived from
the 500-KHz sine wave output of the fundamental frequency
filter 266. One input of the multiplier 318 is the 500-KHz
sine wave fro~ the fundamental frequency filter 266. The
other input of the multiplier 318 is a compensated
saturation control signal. The compensated saturation
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1 326288 PATENT
333-2052
control signal modifies the amplitude of the 500-KHz sine
wave from the fundamental frequency filter 266 to produce
~ the output signal for the multiplier 318.
- The compensated saturation control signal is
developed at the output of the summation circuit 320. One
input of the summation circuit 320 is provided by the
- potentiometer 322, which delivers a portion of the variable
vector saturation control signal to the summation circui~
320. In order to generate the other input for the summation
;~ circuit 320, a portion of the variable vector hue control
signal is supplied by a potentiometer 324 to a squaring
i circuit 326. The squaring circuit 326 squares the input
. .
signal and delivers an output signal to the summation
,
circuit 320. The output of the summation circuit 320 is a
saturation control signal which has been corrected for
changes in the hue control signal. Therefore, the hue of
the variable vector may be changed without altering the
,-' saturation of the variable vector.
..;
;~, The sample-and-hold circuits 312-316 sample a 500-
~'~ KHz sine wave whose amplitude has been modiied by the
,':
compensated saturation control signal, as noted above. The
one-shot circuits 306-310 trigger the sample-and-hold
circuits 312-316, respectively, and the one-shot circuits
306-310 are triggered when the output signals from the
~.,,
comparators 294-298, respectively, change from negative to
positive. The plus inputs of the comparators 294-298 are
supplied by the summation circuits 300-304, respectively.
One input of each of the summation circuits 300-304 is
- supplied by the ramp generator 270, while the other input is
a reference signal. The reference signals for the summation
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1 326288 PATENT
333-2052
circuits 300-304 are cet 80 that the sample-and-hold
circuits 312-316 sample the output of the multiplier 318 at
points which are 120 degrees apart along the associated sine
wave. The minus inputs of the comparators 294-298 are
provided with a compensated hue control signal.
The compensated hue control signal is developed at
the output of a summation circuit 328. One input of the
summation circuit 328 is the variable vector position
control signal, and the other input the summation circuit
328 is from a multiplier 330. A portion of the variable
vector saturation control signal is sent by a potentiometer
332 to the minus input of a comparator 334. The plus input
of the comparator 334 is a reference signal. The difference
between the reference signal and the portion of the variable
vector saturation control signal is delivered to one input
of the multiplier 330. The variable vector hue control
signal is furnished for the other input of the multiplier
330. Accordingly, the multiplier 330 produces as an output
a hue control signal which has been corrected for changes in
the saturation control signal. Thus, the saturation of the
variable vector may be changed without altering the hue of
the varia~le vector.
The output signal from the multiplier 330 is sent to
one input of the summation circuit 328. The summation
circuit 328 adds this signal to the variable vector position
control signal and delivers its output signal to the minus
inputs of the comparators 294-298. Consequently, the
ramp-plus-reference signals at the outputs of the summation
circuits 300-304 are compared to the compensated hue control
signal. The compensated hue control signal corresponds to
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1 3 2 6 ~ 8 8 PATENT
333-2052
the position of the hue corrected variable vector. The
ramp-plus-reference si~nals are used to resolve the hue
corrected variable vector signal into its R, G, and B
components.
The ramp-plus-reference signals toqether with the
summation circuits 300-304, the comparators 294-298, the
one-shot circuits 306-310, and the sample-and-hold circuits
312-316 cause the 0, 120, and 240 signals to be 120
degrees from one another since reference si~nals are set
appropriately. Hence, the hue corrected variable vector
signal may be resolved into its R, G and B components. The
compensated saturation control signal varies the amplitude
of the sine wave sampled by the circuits 312-314. Thus, the
compensated saturation control signal changes the magnitudes
of the 0, 120, and 240 signals to provide a correction
for the saturation level of the variable vector signal.
Level Discrimination Circuit
Figure 10 is a schematic diagram for the level
discrimination circuit 244 shown in Figure 8. The signal
from the output of the four-quadrant multiplier 236 enters
the level discrimination circuit 244 on a line 340. This
signal travels through a resistor R26 to the emitter of a
transistor Ql and through a resistor R25 to the emitter of a
transistor Q2. The base of the transistor Ql is biased by
the potentiometer R16 and the resistors Rl7, Rl9, R21, and
R23 to prevent the conduction of all signals from the
emitter to the collector when the discrimination control
signal is zero or positive. The base of the transistor Q2
is biased by the potentiometer R15 and the resistors R18,
R20, R22 and R24 to permit the conduction of all signals
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1 3 2 6 2 8 8 333-2052
from the emitter to the collector if the dis~rimination
control ~ignal is zero. A diode CRl prevents the bias of
the ~ransistor Q2 from being changed by the discrimination
control signal when the discrimination control signal is
negative.
The bias for the transistor Ql establishes
one discrimination level, and the bias for the transistor Q2
establishes another discrimination level. The level set by
the bias circuit for the transistor Ql is higher than the
level set by the bias circuit for the transistor Q2.
Signals below the associated discrimination level are
prevented from passing to the output, while signals above
the associated discrimination level are passed to the
output.
If the discrimination control signal is zero, the
transistor Q1 passes no signals because the associated
discrimination level is relatively high, and the transistor
Q2 passes all positive signals because the associated
discrimination level is zero. Accordingly, the signal on
`:.4,'
line 248 minus the signal on line 250 has a waveform like
that shown in Figure 11A when the input signal to the color
correction circuit is provided by a device which generates a
spectrum of color signals.
As the discrimination control signal becomes
increasingly positive from zero, the discrimination levels
associated with the transistors Ql and Q2 increase. The
transistor Q1 passes no signals because the associated
discrimination level is even higher than it was for a zero
discrimination control signal. The transistor Q2 passes
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1 326288 PATENT
333-2052
only signals above the associated discrimination level.
Consequently, the signal on line 248 minus the signal on
line 250 has a waveform like that shown in Figure llB. The
discrimination level for the transistor Q2 is determined by
the discrimination control signal, which affects the bias of
the transistor Q2 through the resistor ~20.
As the discrimination control signal becomes
increasingly negative from zero, the discrimination level
associated with the transistor Ql decreases, but the
discrimination level associated with the transistor Q2
remains at zero due to the diode CRl. The transistor Ql
passes only signals above the associated discrimination
level. The transistor Q2 passes all positive signals. As a
result, the signal on line 248 minus the signal on line 250
has a waveform like that shown in Figure llC. The
discrimination level for the transistor Ql is determined by
the discrimination control signal, which affects the bias of
the transistor Ql through the resistor Rl9.
The sign and the magnitude of the discrimination
control signal may be adjusted by the operator with the
factor control 84 (Figure 2) on the front panel 12 of the
color corrector 11. For instance, a clockwise rotation of
the factor control 84 may correspond to a positive
discrimination control signal, and a counterclockwise
rotation of the factor control 84 may correspond to a
negative discrimination control signal. The amount of
rotation, clockwise or counterclockwise, sets the magnitude
of the discrimination control signal.
The factor control 84 and the level discrimination
control circuit 244 provide the opcrator with greater
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1 32 6 2 8 8 PATENT
333-2052
selectivity for the color correction of particular objects.
For instance, if two objects in the video picture are
approximately the same color, but one has a relatively high
saturation level and the other has a relatively low
saturation level, the operator may select one of the objects
to receive color corrections by suitably adjusting the
factor control 84. The video picture signals for the other
object will not receive the color corrections. More
specifically, the operator may distinguish a light blue sky
from a dark blue shirt with the factor control 84 even
though these two objects have the same hue. Then, color
corrections may be developed for the selected object.
Because of this ability, the overall quality of the color
corrected videotape is improved since the operator may
develop color corrections not previously possible.
Other Variations
Even though the color corrector 11 is shown with
one set of variable vector controls, the color corrector may
be equipped with two or more sets of variable vector
controls. Accordingly, two or more principal colors may be
selected, one principal color by each set of variable vector
controls. In fact, a color corrector may have a sufficient
number of variable vector controls to allow the elimination
of the six-vector controls 16 ~Figure 2). However, the
combination of the six-vector controls with the variable
vector controls in a single color corrector is particularly
advantageous. The six-vector controls usually provide
separation of the color corrections from one another which
is adequate for most color correction jobs. Since the use
of the dedicated knobs of the six-vector c-ontrols can be
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1 326288 PATENT
333-2052
quite fast, the speed of operation of the equipment using
both types of controls can be fast as well as high quality.
While the level discrimination circuit is shown
and described in connection with the variable vector control
circuit, one or more of the color correction circuits for
red, green, blue, magenta, yellow, and cyan may be furnished
with such a level discrimination circuit.
The coefficient processor is illustrated and
explained with analog signal processing circuits, but a
suitably programmed general purpose computer or
microprocessor may be employed in lieu of the analog signal
processing circuits. In addition, digital circuits may be
used for other components in the variable vector control
circuits.
Although particular illustrative embodiments
of the present invention have been described herein with
reference to the accompanying drawings, the present
invention is not limited to these particular embodiments.
Various changes and modifications may be made thereto by
those skilled in the art without departing from the spirit
or scope of the invention, which is defined by the appended
claims.
.~
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