Note: Descriptions are shown in the official language in which they were submitted.
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IMAGE PROCESSTNG SYSTEM
This application is a division of application No. 2,106,41,
filed September 17, 1993.
BACKGROUND OF THE IrtVENTION
The present invention relates to an image processing
system, and more particularly to a game computer system
processing a variety of images such as a natural picture
together with an animation picture.
In a conventional game computer system, image data are
defined by color for each dot. The colors of the image data are
managed by a color pallet formed in a memory, the color pallet
storing many pallet codes (PLT) corresponding to color data.
Tn the conventional game computer system, image data
are compressed (encoded) to be transmitted, and then the
compressed data are extended (decoded) to be. displayed. Each
piece of image data is composed of the pallet code {PLT) and the
number {CRL) thereof, which is called a pallet length. The
compression method is called a "run-length" method.
When a single color mode is employed for each screen,
image data may be fixed in length (bits); however, when plural
color modes are used for one screen, the lengths of the image
data are different depending on the color mode.
Fig. 1 shows the formats of image data according to
the conventional game computer,system, which employs 16, 32, 64
and 128 color modes . The pallet codes are defined by data of 4,
5, 6, and 7 bits for the 16 , 32, 64 and 128 color modes,
respectively. The length "L" of the pallet code in a color mode
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"m" is given by the following equation.
L = loge m
For example, the length "L" of the pallet code in the
128 color mode becomes "7" as follows:
L = loge 128 = loge 2'
The data needs to have a width corresponding to a bus
line to be transmitted thereon, because the widths of buses vary
depending on the system.
When the image data are transmitted on a 8 bit bus,
the data for the 16 color mode may be transmitted in entirely,
as shown in Fig. 1; however, when the length of the image data
to be transmitted is not a multiple of 8 bits,' the data need to
be divided, as shown in Fig. 2. For example, image data for the
32 color mode are compressed to 9 bits, the data are divided as
8 and 1 to be transmitted, and as a result, the left over one
bit is transmitted with the following data.
In the conventional game computer system, when the
screen is divided into plural areas of different colors, the
color mode of the greatest number is selected, because each
picture is displayed using only one color mode. For example,
when an animation picture with 16 colors and a natural picture
with 16M colors are synthesized on the screen, the synthesized
picture is displayed in the 16M color mode. Such a processing
method is not effective for using the memory.
SUr~IARy OF THE INVENTTON
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Accordingly, it is an object of the present invention
to provide an image processing system in which the foregoing
disadvantages are obviated or at least mitigated.
Thus, according to the invention, there is provided an
image processing system, in which image data are processed in
a plurality of color modes, comprising:
means for horizontally dividing a screen into plural
blanking areas;
means for specifying color modes for each divided
blanking area; and
means for displaying the image data in accordance with
the specified color modes.
BRIEF DESCRIPTION OF THE DRAWINGS
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Fig. 1 is a diagram showing the arrangements of color
data according to a conventional game computer system.
Fig. 2 is a diagram showing the operation for
transmitting image data according to the conventional game
computer system.
Fig. 3 is a diagram showing the operation for
transmitting image data according to the conventional game
computer system.
Fig. 4 is a diagram showing the operation for scanning
a screen.
Fig. 5 is a diagram showing a relation between a
screen and color vectors thereon.
Fig. 6 is a diagram showing a relation between real
and virtual screens.
Z5 Fig. 7 is a diagram showing the operation for
scrolling the real screen on the virtual screen.
Fig. 8 is a diagram showing a relation between dots on
the real screen and a color pallet
Fig. 9 is a block diagram showing a computer system
according to the invention.
Fig. 10 is a block diagram showing an image extension
unit, shown in Fig. 9,~according to the invention.
Fig. 1I is a diagram showing the operation for
transmitting image data according to the invention.
Figs. I2A to I2E are diagrams showing the
configurations of transfer control, start address, transfer
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start, transfer block number and raster monitoring registers,
respectively.
Fig. 13 is a diagram showing a relation between vector
factors and dots on the real screen according to the invention.
5 Fig. 14 is a diagram showing a relation between dots
on the real screen and a color pallet according to the
invention.
Fig. 15 is a block diagram showing the operation for
transmitting image data according to the invention.
Fig. 16 is a diagram showing a relation between
compressed image data and displayed dot image on the screen
according to the invention.
Fig. 17 is a picture to be displayed by the image
processing system according to the invention,
Fig. 18 is a diagram showing the format for run-length
image data according to the invention.
Fig. 19 is a diagram showing the screen divided into
plural areas according to the invention.
Fig. 20 is a diagram showing the configuration of
image data to be transmitted according to the invention.
Fig. 21 is a timing chart for transmission of image
data when the real screen is not scrolled, according to the
invention.
Fig. 22 is a timing chart for transmission of image
data when the real screen is scrolled one dot to left, according
to the invention.
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Fig. 23 is a timing chart for transmission of image
data when the real screen is scrolled one dot to right,
according to the invention.
Fig. 24 is a timing chart for transmission of image
data to a video encoder unit when the real screen is not
scrolled, according to the invention.
Fig. 25 is a timing chart for transmission of image
data to the video encoder unit when the real screen is scrolled
one dot to left, according to the invention.
Fig. 26 is a timing chart for transmission of image
data to the video encoder unit when the real screen is scrolled
one dot to right, according to the invention.
Fig. 27 is a diagram showing the operation for
transmission between the image extension unit and video encoder
unit according to the invention.
Fig. 28 is a table showing color vectors to be read
and displayed in each scroll mode according to the invention.
Fig. 29 is a diagram showing the arrangement for YYUV
color data in a memory according to the invention.
Fig. 30 is a block diagram showing a control unit,
shown in Fig. 9, according to the invention.
Fig. 31 is a diagram showing the format for compressed
image data in the memory according to the invention.
Fig. 32 is a diagram showing the format for compressed
image data in each color mode according to the invention.
Fig. 33 is a diagram showing a sample picture, in
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which animation and natural pictures are synthesized, according
to the invention.
Fig. 34 is a diagram showing the operation for
synthesizing the sample picture shown in Fig. 33, according to
the invention.
Fig. 35 is a diagram showing a sample picture, in
which plural color mode are employed for one screen, according
to the invention.
Fig. 36 is a diagram showing the data formats
l0 depending on the color modes according to the invention.
DETAIIDED DESCRIPTION OF THE INVENTION
Fig. 4 shows a video screen used in a game computer
system. In this screen, horizontal and vertical scrolls are
performed in H and V blank periods, respectively. The H and V
blank periods are called horizontal and vertical fly-back
periods, respectively, because a scanning line returns back in
these periods. Image data are processed in the fly-back
periods, and the data are displayed on a video screen (CRT) in
accordance with predetermined display timings. The image data
are defined by color data for each dot, the color data being
specified by a RGB or YW system.
The color data are specified for each raster, such as
(C0, . C1, C2, - - -, Cn-1) shown in Fig. 5; the data unit is
called a color vector. The color vector is composed of color
vector factors C0, C1, C2, - - -, Cn-1. In this case, the
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color-vector factors correspond to dots of image data one for
one. Image data to be displayed are read from a virtual screen,
which is derived from a video RAM (VR.AM), in a H-blank period
for the previous image data, so that the image data are
displayed in the next H-blank period.
The virtual screen is formed to be larger than the
real screen (CRT), so that a part of. the virtual screen is
displayed on the real screen. In the virtual screen, an area to
be displayed is specified by coordinates BXR and BYR, as shown
in Fig. 6. The coordinates BXR and BYR are specified in dot and
raster by BGX and BGY registers, respectively. When the BGX
register is set at "BXR-X°', the real screen is scrolled "X" dots
to the right, as shown in Fig. 7. When the image data are read
from the virtual screen in the previous raster-transmission
period, the BGX register becomes effective from the next raster.
If color-vector factors do not correspond to dots in
the real screen one for one, some problems occur.
For a conventional game computer that mainly treats
animation images, it is sufficient to use a small number of
2d color such as 4, 16 or 256 colors to display image. In general,
color data are specified for each dot by color information
stored in a color pallet, as shown in Fig. 8. When the game
computer also treats a natural picture, many colors more than
those for the animation image are required. If the colors of
the natural picture are specified by the color pallet system,
the color pallet is required to have a very large capacity. On
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the other hand, if color data corresponding to each dot are used
to display a natural picture, a large capacity of memory is
required as well.
Fig . 9 shows a computer system, which includes a game
s software recording medium I00 such as a CD-ROM, a CPU 102 of the
32-bit type, a control unit 104 for mainly controlling
transmission of image and sound data and interfacing most
devices to each other, an image data extension unit 106, an
image data output unit, a sound data output unit 110, a video
encoder unit 112, a VDP unit I14 and a TV display I16. Control
unit 104, image data extension unit 106, video encoder unit 112
and VDP unit 114 are mounted on a common TC chip.
CPU 102, control unit 104, image data extension unit
106 and VDP unit 114 are provided with their own memories M-RAM,
I5 K-RAM, R-RAM and V-RAM, respectively.
Image data registered in the CD-ROM are read by the
control unit, so that the image data are buffered in the K-RAM,
and the image data are compressed to be transmitted to the image
data extension unit. The compressed data are decoded by the
image data extension unit, and are supplied to the video encoder
unit. The video encoder unit processes image data supplied from
the controller chip and the other devices to display the image
data on the TV monitor.
Fig. 10 shows image data extension unit 106. The
function of the image data extension unit is now explained. In
this figure, a data bus buffer 200 stores image data supplied
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from the control unit and the like. The image data are divided
into plural blocks to be transmitted.
External memory "R-RAM ~." and "R-RAM B" 202 and 204
store decoded data. Each of the memories has a capacity for 16
5 rasters (64K bits). These memories are used alternatively to
increase the process speed of image data.
The image data extension unit treats IDCT and run-
length images. The IDCT image represents a moving-natural-
picture which is produced by IDCT decoding. The run-length
10 image represents a moving-animation-picture which is compressed
in accordance with run-length data. In each of the IDCT and
run-length image, compressed image occupies "256 dots x 240
rasters" for each field. For the IDCT image, 1677 display
colors are used. The run-length image are displayed in four
run-length color modes of the pallet system, 16, 32, 64 and 128
color modes.
The image data extension unit also includes data bus
terminals KRO to KR7 for receiving data transmitted from the
control unit, and data request terminal -REQR for supplying a
data request signal to the control unit . In response to the
request signal, compressed image data are supplied from the
control unit'. That is, "-REAR = 0" and "-REQR = 1" represent
data request and data stop, respectively. .
The image data extension unit needs to decode the
compressed image data of 16 rasters within a 16 raster period.
For that reason, 16 raster data begin to be transmitted to the
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image data extension unit in a Z6 raster period prior to its
display time so that its transmission processing is finished
before the previous image is finished being displayed.
The image data extension unit has no information on
where the screen is scanned to, and therefore, image data are
transmitted in accordance with a signal from the control unit.
Image data stored in the image data extension unit are displayed
in synchronization with a HSYNC signal supplied from a time 16
rasters after the image data are supplied from the control unit.
Fig. 1l shows the operation of the display timing of
image data on the video screen. In this embodiment, when a
third data of 16 rasters are displayed on the video screen (real
screen), a fourth data of I6 rasters are transmitted from the
control unit to the image data extension unit, and the
transmission is finished before the third data are finished to
be displayed on the video screen completely. The process is
repeated so that image data for one screen are displayed on the
video screen; this is called "normal reproduction'°.
The image data extension unit has an FIFO (First In
First Out) memory for storing image data supplied from the
control unit . The FIFO supplies a disable signal ( -REQR = 1 ) to
the control unit to stop transmitting data temporarily when the
FIFO is filled up with data.
Figs. 12A to 12E show the configurations of registers
built in the control unit. These registers are a transfer
control register shown in Fig. 12A, a start address register
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shown in Fig. 12B for the image data extension unit, and a block
number register shown in Fig. 12D.
The transfer control register stores data for
specifying enabling and disabling of data transmission. When a
disable signal is supplied from the transfer control register to
the image data extension unit while some data are transmitted
from the image data extension unit, the data transmission is
stopped.
The start address register stores data for specifying
an initial address of the K-RAM, which stores data for the image
data extension unit. It begins with the initial address to
transmit data stored in the K-RAM through the control unit.
When block data are treated, an access address of the data is
increased automatically.
The transfer start register stores data for
instructing the start of transmitting data for each raster.
When the instruction signal is supplied to the control unit,
image data are transmitted from the control unit to the image
data extension unit.
The transfer block number register stores data for
specifying the number of blocks to be transmitted to the image
data extension unit, each block being composed of 16 rasters.
If the contents of any registers are not changed, the
same image is again displayed on the same frame. Basically, the
registers become effective instantly after their setting;
however, when the register is set while a data block is
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transmitted to the image data extension unit, the register
becomes effective after the transmission.
The control unit transmits image data to the image
data extension unit, only when the K-BUS has. been arbitrated,
the image data extension unit has been ready to be accessed and
the request signal {-REQR = 0) has been supplied from the image
data extension unit. On the other hand, data transmission by
the control unit to the image data extension unit is disabled
when at least one of the following conditions is met:
(1) The image data extension unit has not processed any
data yet.
( 2 ) The image data extension unit has the FIFO in the full
state.
(3) While HSYNC are counted by 16 times since the first
data of 16 lines are received by the image data extension unit,
the data have been read entirely.
Therefore, when a first bit of data to be transmitted
is disabled, no data is transmitted.
This computer system employs 16, 32, 64, 12$ and 16M
color modes, and a YUV system for displaying colors. According
to the YUV system, colors are defined by a brightness (Y) and
color differences (U, V).
In the 16, 32, 64 and 128 color modes, the color
pallet is used to specify the color; however, in the 16M color
mode, color data corresponding to the color to be displayed are
specified directly in order to use the memory effectively.
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If 4 bit color data are used to specify 16 colors, the
colors are fixed. According to the color pallet, color data for
512 colors may be selected from 65536 colors so that desired 16
colors may be selected flexibly. For each screen, the color
pallet is specified using 4 bit data, and an offset value of the
color pallet is specified.
In general, 24 bit data are necessary for each dot to
display image, and therefore, 224 bit data are necessary in the
16M color mode, as shown by the following equation.
16M = 16 x 1K x 1K = 24 x 101° x 101° = 224
In the YUV system, each of Y, U and V is defined by 8
bit data. Because, the virtual screen formed in the K-RAM has
an area of 1024 x 1024 dots, 24M bits memory is necessary in the
16M color mode.
Because the 16M color mode is generally employed only
for natural pictures taken by a video camera, an image scanner
and the like, the virtual screen is not necessarily required.
That is, it is sufficient to use the memory capacity of 1.5M
bits in the 16M color mode, the memory capacity corresponding to
the real screen, which is about one sixteenth that for the-
virtual screen. In the 16M color mode, in order that 16 bit
color data are used for each dot on the average, the color
vectors are indicated as follows:
(YO Y1 UO V0, Y2 Y3 U1 V1, -- - - -, Yn-2 Yn-1 Um Vmj,
where m = (n - 1j / 2.
The color vector in the 16M color mode is shown in
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Fig. 13. In this case, the next two dots have the same UV
values, that is; only the brightness values Ys are different
from each other. Because the next two dots in natural pictures
are not very different from each other in color, the above
5 mentioned color vector may be used. The two dots are indicated
by color data of 32 bits, and as a result, each screen may be
displayed by using 1M bit data.
In the 16M color mode, each color-vector factor
manages 2 dots. When the screen is scrolled by odd dots
I0 horizontally, timing for reading color data becomes important,
because dot data not to be displayed are transmitted from the
memory.
In the computer system, as shown in Fig. 14, the color
pallet stores pallet codes corresponding to the color data. The
15 video screen is composed of 61440 (256 x 240) dots. In the 16M
color mode, each color data are defined by 4 bits, and
therefore, 30K bytes data (61440 x 4 - 245760 bits - 30720
bytes) are necessary to display one picture. If such a large
amount of data are processed directly, it takes very long time
to transmit them.
For that reason, image data are compressed (encoded)
to be transmitted, and then the compressed data are extended
(decoded) to be displayed, as shown in Fig. 15. Each image data
are composed of a pallet code (PLT) and the number (CRL) of the
code, as shown in Fig. 16. The number (CRL) is called a pallet
length or run-length, and the compression method is called a
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run-length method.
In the computer system, compressed data supplied from
the control unit are extended by the image data extension unit
to be reproduced, and then the data are stored in the RRAM.
After that, the data are read from the RRAM for each color
vector in accordance with a DCK cycle, and then the data are
transmitted to the video encoder unit. According to the
invention, timings for reading and transmitting data are
controlled well to realized a Horizontal scroll.
When color-vector factors are read from the RRAM with
"read-timing", the color-vector factors are separated into
brightness "Y" and color differences "U" and '°V", and therefore,
the image data are displayed on the screen without scroll. The
read-timing is shifted in order to realize a horizontal scroll.
The amount of the shift varies depending on whether the picture
is scrolled by odd or even dots.
When the image data is scrolled by even dots, the
color-vector factors are read at a timing for horizontal scroll,
and the color-vector factors are transmitted at the same timing .
All image data to be displayed do not always correspond to color
vectors to be read. For example, image is scrolled by two dots
to the left (horizontal scroll +2 ) , and a color vector (Y2 Y3 U1
Vl, - - - - - Yn-2 Yn-1 Um Vm, Z) is read, where m = (n-1) / 2.
Which data is read first is specified by a SCX register, which
stores a value corresponding to BXR (count value) shown in Fig.
6.
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Image data out of the real screen varies to be
displayed depending on the scroll mode. In an endless scroll
mode ( "Chazutsu mode" } , the outside data are displayed to be "YO
Y1 UO VO", and in a non-endless scroll mode ("non-Chazutsu
mode), the outside data are displayed as transparent. In the
endless scroll mode, color-vector factors scrolled out from one
end of the real screen are again displayed from the other end.
When a picture is scrolled by odd dots at a timing
shifted by one dot from a timing that is used for a non-scroll
mode, the first color-vector factor is not read in the display
period (HDISP}. For example, when a picture is scrolled by 3
dots to the left (horizontal scroll +3), the vector (Y2 Y3 U1
V1, Y4 Y5 U2 V2, - - - -, Yn-2 Yn-1 Um Vm, Z} is transmitted,
where m = (n-1 ) / 2 . This vector is the same as that in the
case of the two dot scroll; however, the reading timing is
shifted so that "Y2 U1 V1" factors are not read in the display
period, and as a result, the picture is scrolled by three dots.
In this embodiment, color data and run-length have a
length which is an integral multiple of a length of each data
block for image data to be transmitted.
Fig. 17 shows an example picture, which is displayed
by the colors as shown in the figure, where the colors in
parenthesis indicate colors for a monochrome mode: On a line
"a-a", the color of the picture varies in the order of blue
(65), red (20), white (15), red (40), grey (20), green (20) and
grey (60}, where the figures in the parenthesis indicate the
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numbers of dot corresponding to run-length for compressed data.
In the monochrome mode, the color of the picture varies in the
order of white (65), black (20), white (15) and black (140).
The more the number of the color is increased, the
more the run-length is shortened. In this embodiment,
compressed data are formed to meet the following three
conditions, as shown in Fig. 18:
(1) Compressed data are formed to have a length which is
integral multiple of the width of the data bus (fixed length).
(2) Run-length is shortened in accordance with increment
of a pallet code (PLT).
(3) If a run-length {CRL) is so large that the data can
not be contained in the fixed length, the run-length is not
transmitted with its data code and is contained in the following
record itsself. This processing is called an "expansion mode".
According to the embodiment, the screen is divided
into a plurality of horizontal blankings (nH) each composed of
n-rasters, as shown in Fig. 19, so that a picture is displayed
on the screen in plural color modes for each "nH" (n rasters).
The above mentioned processing is realized in
accordance with the following steps, so that a color mode to be
used and a color code are determined for each "nH" and dot,
respectively:
( I ) Detecting all color modes used in a picture to be
displayed.
( 2 ) Detecting a color mode of the largest number, and
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using the color mode for the block.
(3) Rewriting color data in the horizontal blankings
in accordance with the color mode.
Such data are transmitted to another device as shown
in Fig. 20, that is, the data has a marker code at the top and
color data following the code.
This system uses VSYNC (V-blank) and HSYNC (H-blank)
interrupt signals and a DCK signal to control display of image.
When the HSYNC signal is supplied from the video encoder unit to
the other devices, an interrupt operation is carried out, and
compressed image data are transmitted for 16 rasters from the
control unit to the image data extension unit. The image data
extension unit reproduces the image data to be stored in the
RRAM. In response to the DCK signal, an interrupt operation is
carried out for each dot.
Next, the operation of horizontal non-scroll (0) and
one dot scrolls to the left (+1 ) and right (-1 ) is now explained
in conjunction with Figs . 21 to 26 . Figs . 21 to 23 and 24 to 26
show timings for reading and transmitting data, respectively.
How many dots by which the screen is scrolled depends on the
first colo-vector factor to be read, and whether odd or even
scroll is performed depends on the timing for transmitting the
image data. In Figs. 24 to 26, "RTO to RT7" and "RTCODE 1 to
RTCODE 0" represent the types of data bus and types of image
data on the data bus, respectively.
In response to a read-timing signal, first data (YO Y1
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U0 VO) are read to be separated from each other, as shown in
Fig . 21, and the separated data are transmitted to the video
encoder unit so that non-horizontal scroll is performed. When
the first dot is displayed, the next data (Y2 Y3 U1 V1 ) are
5 buffered, and the processing is repeated to display the image
entirely.
The first data (YO Y1 UO VO) are read from a time two
clocks prior to the read-timing, as shown in Fig. 22. At this
time, data (YO UO V0) are buffered; however, the data are not
10 displayed by an INVALID signal because the data are not in a
display period. Therefore, the image data are displayed from
data (YO UO VO), that is, the image is shifted one dot to the
left. In this case, when the last dot becomes invalid, the data
(YO UO VO) and invalid signal are transmitted to the video
15 encoder unit in the endless and non-endless scroll modes,
respectively. As a result, the last dot is displayed as being
transparent in the non-endless scroll mode.
The first data (YO Yl UO VO) are read at a time two
clocks after the read-timing, as shown in Fig,. 23, so that the
20 first dot is not displayed and the data (YO UO VO ) are displayed
from the second dot timing. As a result, the screen is scrolled
by one dot to the right in the non-endless scroll mode. In the
endless scroll mode, when the last color-vector factor (Yn-2 Yn-
1 Um Vm) is read with the same timing as the case of the one-
dot-left scroll, shown in Fig. 22, data (Yn-1 Um Vm) are
displayed at the first dot on the screen.
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When the YYUV type of data are transmitted to the
video encoder unit, the data are decoded into YUV data by the
unit. When the YUV data are not in the display period, the data
are not displayed so that the horizontal scroll is performed.
Fig. 27 shows a relation between the image data
extension unit and video encoder unit.
Fig. 28 shows color vectors to be read and displayed
in each scroll mode. In this table, "m," INVALID," DELAY
TIMING," +" and "-" represent (n-1)/2, no-display (transparent),
delay time of the first vector factor from the read-timing,
reading earlier and later, respectively.
Fig. 29 shows the arrangement for YYUV color data in
the memory.
As described before, according to the invention,
timings for reading and transmitting data are controlled to
perform a horizontal scroll. As a result, even if color-vector
factors do not correspond to dots in the screen one for one, a
horizontal scroll may be realized smoothly.
Next, a second preferred embodiment will be explained.
This embodiment also employs the computer system shown in Fig.
9.
CPU 102 directly controls a DRAM via a memory support,
and performs communication through an I/0 port to peripheral
devices, that is called an I/0 control function. CPU 102
includes a timer, a parallel I/0 port and an interruption
5 control system. VDP unit 114 reads display data which have been
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written in the VRAM by CPU 102. The display data are
transmitted to video encoder unit 112 whereby the data are
displayed on the TV display 116. VDP unit 114 has at most two
screens each composed of background and sprite images, which are
of an external block sequence type of 8 x 8 blocks.
Fig. 30 shows control unit 104. Control unit 104
includes an SCSI controller to which image and sound data are
supplied through an SCSI interface from CD-ROM 100. Data
supplied to the SCSI controller are buffered in the K-RAM:
Control unit 104 also includes a DRAM controller for reading
data which have been buffered in the K-RAM with a predetermined
timing. In control unit 104, priority judgement i.s carried out
for each dot of natural background image data, and an output
signal is transmitted to video encoder unit 112.
Control unit 104 transmits moving image data (full
color, pallet), which have been compressed, to image data
extension unit 106 whereby the compressed data are extended.
Image data extension unit 106 includes an inverse DCT
converter, an inverse quantizing means, a Huffman coding and
decoding means and a run-length coding and decoding means . That
is, the image data extension unit 106 performs a DCT
transformation for a natural moving picture, and treats
compressed data encoded by the Huffman coding method and run
length compressed data for a moving animation image and the
like.
Video encoder unit 112 superimposes VDP image data,
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23
natural background image data and moving image data ( full color,
pallet) transmitted from VDP unit 114, control unit 104 and
image data extension unit 108. Video encoder unit 112 performs
color pallet reproducing, special effect processing, D/A
converting and the like. Output data of video encoder unit 112
are encoded into an NTSC signal by an external circuit.
ADPCM sound data recorded in CD-ROM 100 are buffered
in the Ii-RAM and then transmitted to sound data output unit 110
by control unit 104. The sound data are reproduced by sound
data output unit 110.
Fig. 31 shows the format for compressed image data in
the memory. In this embodiment, pallet colors in 16, 32, 64 and
128 color modes are employed to display images. Image data are
transmitted for 16 rasters (lines} through a data bus of 8 bits.
According to the system, plural color modes may be used for one
screen; however, 16 raster data are displayed in a single color
mode.
In figure 31, "A" specifies the type of image data.
In the area "A", each of "FFH" and "F8H" represents IDCT
compressed data for a natural picture. On the other hand, each
of "F3H," F2H," F1H" and "FOH" represents image data with a
color pallet for an animation picture. "F3H," F2H," F1H" and
"FOH" represent run-length compressed data of 128, 64, 32 and 16
colors, respectively. "B," C°° and "D" represent the first and
last halves of bytes of a compressed data region and data for
two byte boundary of compressed data, respectively.
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Fig. 32 shows the format for compressed image data in
each color mode, which are stored in a compressed data region.
In the 64 color mode, a region for run-length has 2 bits, and
therefore, "4" is the maximum for binary number in the region.
For that reason, for example, when 100 dots of a color
corresponding to a pallet code 13 are displayed successively,
"13" and "0" are contained in the first data block, and "100" is
contained in the next data block. In the decoder, when "0"
following the pallet code "13" is detected in the first data
block, "100" in the following data block is judged to be run-
length data, so that 100 of the same color corresponding to the
pallet code "13" are displayed on the screen. If the expansion
mode is not employed, 25 data blocks of "13 + 4" must be
transmitted, and therefore, 200 bits data are totally necessary
in this case.
As described before, according to the second preferred
embodiment, compressed data may be decoded easily, because each
compressed data have a length being integral multiple of the
width of the data bus.
Next, a third preferred embodiment will be explained.
The embodiment also uses the computer system shown in Fig. 9.
The control unit reads image data from the CD-ROM to store the
data in the K-RAM. The control unit reads the data from the K-
RAM, so that the data are rotated, extended or the like, and
then, the processed data are transmitted to the following stage .
In the image data extension unit, a color mode is changed in
CA 02413059 2002-12-18
accordance with a marker code placed at the top of 16H (16
horizontal blankings) data. When no marker code is detected,
the current color mode is maintained to be employed.
In the computer system, animation and natural pictures
5 may be displayed on different BG (background) screens. The
control unit synthesizes four independent BG screens.
When a picture divided along the horizon is displayed,
as shown in Fig. 33, the upper and lower~halves are treated to
be animation and natural pictures, respectively. In the upper
10 half, the blue sky and green mountain are displayed. In the
lower half, people who are wearing colorful clothes and the like
are displayed. This picture is displayed by synthesizing four
BG pictures shown in Fig. 34.
If the picture is displayed only in the 16M color
15 mode, a memory area of 180K bytes (256 x 240 x 3 = 184,320) is
necessary. If the upper and lower halves are displayed in the
16 and 16M color modes, respectively, and the color mode is
changed for each dot, 27 (= 3 + 24) and ? (= 3 + 4) bits are
necessary for each dot in the 16M and 16 color modes,
20 respectively. In this case, 3 bits are used for the marker code
to indicate the color mode. Therefore, a memory area of 127.5K
bytes is necessary to display the picture entirely as follows:
256 x 120 x (27 + 7) - 1,044,480 bits
- 130,560 bytes
25 - 127.5k bytes
According to the preferred embodiment, the color mode
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is changed for each 16H (16 horizontal blankings), and the 16M,
128, 64, 32 and 16 color modes are used to display the picture.
When a 16H-area includes both 16 and 16M color mode
areas, as shown in Fig. 35, the area is displayed in the 16M
color mode. In the picture, when plural 16H-areas having the
same color mode are arranged successively, the color mode of the
previous area is used again for the next area. When each marker
code is defined by 8 bits, approximately 105K bytes data are
necessary to display the picture shown in Fig. 33, as follows:
256 x 120 x (4 + 24) + 8 + 8 = 860,176 bits
- 107,522 bytes
- 105K bytes
The data of 105K bytes corresponds to 58~ of that in
a single color mode of 16M, as shown in Fig. 36.
According to the third preferred embodiment, the
memory may be used effectively, especially when animation and
natural pictures are displayed together, and as a result, image
data may be transmitted at a high speed. Further, encoding
errors may be detected without a restart maker code used in the
conventional system, because a color code is included in each
16H data block. That is, when a code other than the
predetermined color codes is contained, an encoding error is
detected.
