Note: Descriptions are shown in the official language in which they were submitted.
82/246F
MOTION PICTURE SYSTEM
BACKGROUND OF THE INVENTION
In the early development of the motion pic-
ture, experimentation was conducted to determine the
ideal parameters. Perhaps the foremost innovator was
Thomas Edison who designed the 35 mm format which is
still the most widely used theatrical motion picture
format worldwide. Edison chose a frame rate of 48 fps
(frames per second), which is a rate that was found to
avoid observable flickering. However, this rate was later
abandoned by the industry as a result of the work of Louis
and August Lumier who discovered that flashing each frame
a plurality of times can eliminate flicker. They chose a
16 fps rate, but with each frame flashed three times (two
interruptions to provide three brief showings) to obtain
a 48 per second flashing rate which was found to avoid observ-
able flickering while reducing the required amount of
film stock.- A 16 fps rate, with each frame flashed .
twice, produces a continuous and flicker-free ima~e
(at least when the picture quality is not good).
When sound was added to motion pictures in
the late 1920's, a faster film speed was needed so the
sound track could move fast enough past the sound head
to generate good sound fidelity. A rate of 24 fps
with double flashing of each frame, which provides 48
flashes per second, was chosen as the standard. This
rate has continued from that time to the present, and
remains the worldwide standard for commercial theater
motion picture projection. Although considerable
development work has been done on improving motion
picture quality, relatively little has ever been pub-
lished regarding frame rates since the 24 fps double
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flash rate standard was adopted; in fact modern articles
which have been found on the subject suggest that frame
rates of less than 24 fps but with triple flicker should
be considered for modern use. It may be noted that
very high camera frame rates are sometimes used in
scientific experimentation, such as in investigating
the impact of a projectile or the flight techniques of
birds, but the resulting film is shown at a much lower
rate such as 18 fps or 24 fps, but not at the original
camera rate.
Considerable development work has been performed
on improving image quality. The graininess of film
limits its resolution. Graininess probably was not a
problem in the earliest motion picture development by
Edison whose development was concerned with peep show
display (the nickelodeon). Even in early theatrical
display, the problems of accurately aligning subsequent
film frames and other technical limitations probably
overwhelmed film resolution limitations. ~owever, as
camera and projector technology improved, the film
resolution limitations have become important, especially
as bigger and wider screens have been employed. Wider
screens that provide a greater horizontal angle of view
have long been recognized as desirable in providing
greater realism, but they can result in increased
lateral magnification which increases the noticeable
graininess. 70 mm ~tide film was developed in the early
1950's to increase resolution. A technique named Vista
~ ~ Vision~was developed in the late 1950's for the wide
screen, wherein standard 35 mm film was used but each
frame was positioned at a 90 rotation from normal;
thus, instead of using standard film frames 0.825 inch
wide and 0.446 inch tall, Vista Vision used frames about
.870" tall and about 1.470" wide (with the 1.470" dim-
ension extending along the length of the film). A
technique named Cinerama~was developed in the 1950's,
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82/246F 3
wherein three separate ~rojectors using 35 mm film,
were used to obtain good image quality over a very
wide screen. Presently, 70 mm wide film is occasionally
used in commercial entertainment film projection, with
an image area of 1.912 inch by 0.870 inch. While these
techniques ha~-e produced clear, large images in commer-
cial theaters, an even greater degree of realism would
be desirable.
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82/2~6E 4
SU~MARY OF THE INVENTION
In accordance with one embodiment of the
present invention, a method is described for producing
a motion picture image that creates a vivid impression
of realism in observers. A motion picture is photo-
graphed on a strip of film, developed, and projected.
The film has sufficient resolution, each frame is large
enough, and the camera lens has sufficient resolution,
to create a resolution of better than 40 line pairs
per millimeter over an area of at least 230 square
millime-ters (0.36 square inches). At least this
degree of resolution, times the magnification, is also
~resent in the image of each frame projected on the
screen. During projection, an illumination level great-
er than 16 foot lamberts is produced on the screen.
The frame rate at which the film is exposed and later
projected, is a-t least 50 frames per second. The
combination of high resolution of at least 40 line
pairs per millimeter times the projection magnifica-
tion, the high illumination level of greater than 16
foot-lamberts on the screen, and the high frame rate
of at least 50 frames per second, results in creation
of a vivid image of realism in observers who axe view-
ing the projected image.
The novel features of the invention are set
forth with particularity in the appended claims. The
invention will be best understood from the following
description when read in conjunction with the accom-
panying drawings.
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82/246F 5
BRIEF DESCRIPTION OF T~IE DRAWINGS
Figure 1 is a partially elevation and partially
perspective view of a motion picture system of the
prior art.
Figure 2 is a simplified perspective view of
the system of Figure 1.
Figure 3 is similar to Figure 2, except that
it shows the prior art system at a later instant.
Figure 4 is a plan view of a commercial motion
picture theater.
Figure 5 is a view of two lines showing how
resolution can be defined in a system of the present
invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Figures 1 and 2 illustrate a motion picture
projector 10 of a conventional commercial type which
can project images on a screen 12. The projector includes
a light source 14, and a lens 16 that directs the light
through the film 18 and through a lens 20 that focuses
the light onto the screen. An intermittent film feeding
mechanism 22, shown in Figure 2, such as a maltese cr.oss
type that includes a film-engaging sprocket 24, rapidly
moves a film ~rame 18F to a projecting position directly
behind the lens, and holds it there for a short period.
During the time when the film frame is being moved to
the projecting position, a shutter 26 blocks the light
as shown in Figure 3. In present theater systems,
twenty four new film frames per second are positioned
at the projecting position. In order to prevent apparent
flicker however, each new frame is briefly interrupted
by the shutter 26 while the frame is stationary at the
projecting position, so that the frame is shown twice,
or "flashed" twice, which has been found to generally
avoid apparent flickering.
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82/2~6F 6
Although considerable development work has
been done to improve motion picture quality, the effor-ts
have generally involved adjusting the size, orientation,
or the like of the film frame. As described earlier,
much of the work done to improve image quality has
involved the use of a larger film frame size which
reduces the effect of film grain especially for pro-
jection on large wide screens.
In accordance with the present invention,
a method is provided for producing a motion picture
image that creates a vivid impxession of realism in
observers, which is superior to that which has been
previously created in motion picture theaters even
when using wide format film and the best of equipment
in taking and projecting the motion picture film. In
particular, it has been found that when good theater
quality resolution and film frame size is provided
along with the use of a high screen illumination level
that is as high as is used in the best prior motion
picture theaters, that when this is combined with the
use of a very high frame rate of at least 50 frames per
second, that viewers experience a high degree o~ realism
far superior to that which has been reali~ed heretofore
even when high theatre quality motion picuture films
have been projected using high illumination level.
The resolution of the image projected on a
large and high quality theater screen, may be clefined
in different ways. One definition is the number of line
pairs that can be resolved per millimeter. The SMPTE
(Society of Motion Picture and Television Engineers) has
set a standard of 80 line pairs per millimeter. This
"standard" is really a goal and is almost never attained
in practice. Figure 5 illustrates a pair of lines 40,~1
with a space 42 between them, and separated by a distance
D. If the distance D is l/80th mm and the lines can be
82/246F 7
distinguished, then the resolution is at least 80
line pairs per mm. For standard 35mm film frames of
11.3 millimeters (0.446 inch) height, 900 line pairs
can be resolved across the height of the film frame
at a resolution of 80 line pairs per mm on the film.
At a resolution of 40 line pairs per mm, 450 line
pairs can be resolved across the height of the film
frame.
Another definition of resolution or potential
information or storage capacity, can be based on the
proposition that each line and the space between them
can represent rows of pixels, such as the pixels 43, 44,
45. Assuming the same resolution in every direction then
the information capacity is proportional to the area
of the film frame. The "standard" 35 mm film frame has
a width of 21 millimeters (0.825 inch) and a height of
11.3 millimeters (0.446 inch). At a resolution of 80
line pairs per mm, the capacity per film frame based on
the above approach is 13.-7 million pixels. In practice,
professional photographers using typical care and equip-
ment achieve a resolution of about 50% of the SMPTE stand-
ard, or about 40 line pairs per mm, and each 35 mm film
frame then could be said to have a capacity of about 3.4
million pixels. Color film is readily available that
has sufficient grain fineness to permit a resolution of
over 80 line pairs per mm.
A projection lens of high resolution can project
an image of a film frame on a screen, to produce about
the same resolution or capacity of pixels on the screen
as are present on the film frame. That is, for a stand-
ard 35 mm film frame with a resolution of 40 line pairs
per mm, 450 line pairs can be resolved across the height
of the projected image.
As mentioned above, the information capaci-ty
of a film frame depends on both the area of the film
frame and the resolution.
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The following table compares the film sizes
that are available.
Film Type Width Height Area - millimeter
Regular 8mm 4.4mm (.172 inch) 3.3mm (.130 mch) 14.2mm (.022 inch )
Super 8mm 5.3mm (.208 inch) a.Omm (.158 inch) 21.3mm (.033 inch2)
16mm 9.7mm (.380 inch) 7.3nm (.286 inch) 70.3mm (.109 inch2)
"standard" 35mm 21mm (.825 inch) 11.3mm (.~46 inchj 237mm (.368 inch )
Panavision 35mm 21.3mm (.838 inch) 17.8mm (.700 inch) 379mm (.587 inch )
. , .
7Omm 48.6mm (1.912 inch) 22.lmm (.870 inch) 1070mm (1.663 inch )
IMAX 70mm 69.6mm (2.7~) inch) 48.5mm (1.91 inch) 337~m (5.23 inch )
Almost all home motion pictures are taken on a "Super 8"
format, in which the film area of each frame is less than
one-tenth the area of "standard" 35 mm frames. Thus, even
if the camera and techniques used by professional motion
picture photographers were available for home motion pic-
tures, the information capacity per film frame would be
much less than on the 35mm format which is the smallest
used in the commercial theater entertainment motion picture
industry.
The brightness of the image projected on a
screen, is typically measured in terms of the foot lamberts
produced when blank (unexposed) portions of the film are
projected. In an average commercial motion picture theater,
a level of 8 to 10 foot lamberts would be expected, while
in a good quality theater, a level of about 12 foot lamberts
might be expected. The SMPTE has recommended a level of 16.5
foot lamberts, but this is not achieved in practice. The
ANSI (American National Standards Institute) has stated
that the luminance level of 16 + 2 foot lamberts should not
be exceeded or else flic~er becomes objectionable. The
screen brightness that is observed actually depends on the
luminous flux or light intensity projected on the screen
and the reflectance of the screen. We have used a ~urley
Superglow screen having a gain of 2 (a matt white surface
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82/2~6F 9
has a gain of 1.7) to obtain maximum brightness with
good image quality. Assuming light reflectance of 80~,
and a relatively small theater screen which is about 10
feet high and 18 feet wide, a flux of about 3,400 lumen
would be required (at 18.5 lumens per square foot) to
achieve the present high light intensity of 15 foot
lamberts even in a relatively small commercial theater.
A flux of over3700 lumen wo~ld be required to produce
over 16,5 footlamberts.
When professional quality film of a commercial
size of at least the standard 35 mm format, and profes-
sional techniques are used that produce a resolution of
over 40 line pairs per mm, a high quality motion picture
can be obtained wherein each frame has over 3.4 million
pixels of storage capacity. When this film is developed
and then projected, using a high quality theater proj-
ector with a good projection lens, the resolution of the
image on the screen is limited only by the resolution of
the film frame. When such resolution is present along
with a high illumination level approaching the suggested
16.5 foot lambert level, or higher, and with the
standard commercial rate of 24 frames per second is used,
a bright and clear image is produced. However, in
accordance with the present invention, it is found that
when these factors of high reso~ution and light level
are used, and in additon, the frame rate at which the
image was photographed and later projected is at leas-t
50 frames per second and preferably higher, that an
unusual phenomenon occurs. Observers of the resulting
motion picture image experience a vivid impression of
realism which is greatly enhanced from the level achieved
when all the factors are the same except that a slower
frame rate such as 24 fps is used.
Althouqh the projected image quality must be
high, it is not just the information projected on the
~ screen per unit time that results in the realism that
82/~46F 10
applicant obtains. Applican-t has made and shown a
motion picture using the 70 mm format (1.663 square inches
per frame) with a resolution of at least 56 line pairs
per mm, and a frame rate of 60 fps. The vivid impression
of realism that was created, was not matched by similar-
ly high quality motion pictures taken in the IMAX~
format (5.23 square inches per frame, but at a 24 fps
rate) even though the capacity of information, and the
amount of film used, is greater for the I~Ax technique.
For example, assuming 3.4 million pixels per 35 mm
standard frame, there would be 15.4 million pixels per
70 mm frame and 48.3 million pixels per IMAX rame.
At 60 fps the 70 mm frame provides 924 million pixels
per second, while at 24fps the lMAX frame provides
1449 million pixels per second. Still, the 70 mm
frame at 70 fps provides more realism than the IMAX
frame at 24fps. :~ `
While a frame rate progressively greater than
50 fps can produce a progressively superior motion pic-
ture image, there appears to be a limit of about 72 fps
at which a further rate increase does not produce sig-
nificant further improvement. Psychological studies
were conducted by an independent firm, using 52 persons
as subjects, to assess the response of the viewers to
different projection frame rates. Motion pictures of
the same scenes were taken at six different frame rates
at 24, 36, 48, 60, 66 and 72 fps, and were shown to the
subjects at the rates at which they were taken, under
carefully controlled conditions. Although the comments
of viewers show that ~he overall quality of the image
increased with frame rate to about 72 fps, the invol-
untary galvanic skin response showed this even more
clearly.
The vivid impression of realism created by
the use of a high frame rate such as 60 fps, occurs only
~ when the projected image is already clear and brlght as
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82/246F 11
by the use of film frames having a storage capacity of
over 3.4 million pixels per frame, and a high light level
of at least 16 foot lamberts. If the capacity and bright-
ness of the film are rnuch less than these levels, then
the use of a high frame rate above 50 fps will not produce
a vivid impression of realism. It is also necessary
that the photographing and projection be accomplished at
professional levels, wherein the film is evenly exposed
at the proper light level during photographing, and that
the lenses be set to produce a very sharp image during
both the photographing and projecting. All of these
conditions would not be present simultaneously in home
motion pictures iaken on the typical 8 mm or super 8
format. In super 8 format, each frame has an area less
than one-tenth that of a standard 35 mm frame. Even if
a professional level of image sharpness is achieved,
such as a resolution of 40 line pairs per mm, then the
capacity per frame in the super 8 format, of about 0.3
million pixels, is still about l/lOth that available
in commercial theater systems (35 mm stock). Addi-tional
degradation of home movie quality as compared to prof-
essional theater quality, during photographing, dev-
eloping, and projecting, results in an even greater
discrepancy in projected image quality.
It might be supposed that the size of the
film frame should not matter, because home movies are
projected on smaller screens, so the image on a film
frame is distributed over a smaller area of a small
screen; even a theater motion picture may be displayed
on screens of different sizes in different theaters.
However, viewers can properly ~iew a screen containing
a motion picture image only if they place themselves far
enough from the screen to ~riew all or most of the screen
or at least along the height thereof. Figure ~ illustrates
a relatively small screen 110 of a 1.85 aspect ratio
(the width is 1.85 times the height) in a small theater
wherein the seats are arranged within the rectangular
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82/2 ~ 6F 12
area 112 to view a screen of width 1~. The preferred
seating area is indicated at 114, which extends between
distances W/2 and 1-1/2 W from the screen. In a large
theater having a large screen 120 of a width T that is
twice as large as the width W. the seats are typically
arranged within a rectangular area 122 and the ideal
viewing area 124 extends from a distance T/2 to 1-1/2
T from the screen. At the point 126 which is at the
front of both viewing areas 114, 124, the width of the
screen subtends an angle of about 60. Most viewers
will not feel comfortable sitting closer than abou-t this
location because they then cannot view most of the height
of the screen without moving their heads up and down.
It may be noted that wide formats have been found to
enhance entertainment, by providing an image in the
peripheral area of the observer's vision in which
background scenery lies, but the primary portion of the
image usually lies near the center of the screen.
Thus, the invention provides a method for
producing an entertainment motion picture image that
creates a vivid impression of realism in observers that
is superior to that which has been created in the past.
This is accomplished by photographing and later proj-
ecting a motion picture image, where the film frames have
a high information storage capacity to create an im~ge of
high resolution to an observer in the preferred seating
area and are projected at a high light level, at least
equal to high quality theater motion picture standards,
and where, in addition,the frame rate is at least 50 fps.
The information storage capacity of each frame is one
wherein each film frame has a resolution of over 40
line pairs per mm and an area of at least 230 square
millimeters (0.36 square inch), which is that achieved
in good quality photography in the standard 35 mm format.
This provides a storage capacity per frame of over 3.4
million pixels per frame, and at least this capacity is
82/2~6~ 13
available in the image projected on the screen. (Applicant
has set a minimum standard of resolution oE 56 line
pairs per mm and is using the 70 mm format in his films).
The illumination level is at least 16.5 foot lamberts.
When these high quality standards are combined with the
high frame rate of at least 50 fps applicant finds that
an unusually vivid impression of realism is created in
observers of the motion picutre image. of course, it
is usual to make copies of the original film and project
these copies on screens, so that the description of
exposing and projecting a film includes the projecting
of a copy of the original exposed film.
Although particular embodiments of the invention
have been described and illustrated herein, it is rec-
ognized that modifications and variations may readily
occur to those skilled in the art and consequently, it
is intended that the claims be interpreted to cover
such modifications and equivalents.
