Color image processing apparatus

Color image processing apparatus for displaying color images comprised of terminals for receiving pixel data and control data, first and second frame memories for storing the pixel data of 2 picture frames of image to be displayed, and first and second color look-up tables provided correspondingly with the first and second frame memories for storing color data to be referred by the pixel data in the first and second frame memories, which color data are determined individually between the first and second color look-up tables. The apparatus further comprises a control and output device for controlling arrangements of the first and second frame memories and the first and second look-up tables concurrently, and determining the color data to be stored individually in the first and second color look-up tables and outputting color pixel data determined according to the pixel data in the first and second frame memories and the color data in the first and second look-up tables in response to the control data inputted thereto. Further in detail, the control data cause the control and output device to combine the first and second frame memories so as to operate as a single unit and to make up a third look-up table having at least a color data domain equivalent to the first look-up table.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a color image processing apparatus which 
provides improved color image for such applications as CD-Graphics 
displays by utilizing a new form of color look up table. 
2. Description of the Prior Art 
CD-Graphics is a system in which sound is combined with still-picture 
images, and is often used for a KARAOKE(sing along) entertainment. 
However, the CD-Graphics has some deficiencies as follows: 
1) Colors possible to be displayed are limited to 16 colors, thus color 
reproduction and gradation are poor. 
2) Slow picture change due to its low data transfer rate 
3) Monotonous picture change since the picture replacement process 
performed on the same memory layer. 
These deficiencies make the CD-Graphics system less attractive or versatile 
as a media for carrying image information, as a matter of fact, the 
softwares issued in this format are still very limited. In this regard, 
the present invention is directed to offer color image processing 
apparatus capable of presenting more interesting and full variety color 
images. 
SUMMARY OF THE INVENTION 
A primary object of the present invention is to overcome such deficiencies 
as described in the foregoing, and to achieve an improved color image 
processing apparatus for displaying color images. 
According to one concept of the present invention, there provided in an 
apparatus, terminals for receiving pixel data and control data, first and 
second frame memories for storing the pixel data of 2 picture frames of 
image to be displayed, and first and second color look-up tables arranged 
correspondingly with the first and second frame memories for storing color 
data to be referred by the pixel data in the first and second frame 
memories, which color data are determined individually between the first 
and second color look-up tables. The apparatus is further provided with a 
control and output device for controlling arrangements of the first and 
second frame memories and the first and second look-up tables 
concurrently, and determining the color data to be stored individually in 
the first and second color look-up tables and outputting color pixel data 
determined according to the pixel data in the first and second frame 
memories and the color data in the first and second look-up tables in 
response to the control data inputted thereto. 
Further in detail, the control data cause the control and output device to 
combine the first and second frame memories so as to operate as a single 
unit and to make up a third look-up table having at least a color data 
domain equivalent to the first look-up table. 
The invention and its advantages will be best understood from the following 
detailed description when read in connection with the accompanying 
drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Color image processing apparatus according to the present invention will be 
described in detail with reference to the accompanying drawings. 
FIG. 1 is a schematic representation-of a color image processing apparatus 
according to an embodiment of the present invention in which a terminal 10 
is connected to an input of a memory section 14 which includes a first and 
a second frame memories 16 and 18 respectively, and further includes a 
color look up table, hereinafter referred to as "CLT" 20, or 20A and/or 
20B depending on an operating mode thereof. A terminal 12 is connected to 
an input of a memory controller 22 and also to an input of an output 
controller 24 which has 2 other inputs being connected to 2 corresponding 
outputs of the memory section 14. Further, an output of the output 
controller 24 is connected to an input of a display 26. The terminal 10 is 
supplied with pixel data of image and CLT data from an instruction 
processing part (not shown) of CD reproduction section (not shown). The 
terminal 12 is supplied with control data for image displays from the CD 
reproduction section. In order not to read as erroneous data by 
conventional CD Graphics systems, signal formats for commands and 
correction data in this embodiment, are made as such that they are not 
accepted by conventional models of the CD Graphics systems. In practice, 
the subcodes of "R" to "W" are maintained in the conventional format, and 
major pixel data, CLT data, preset and scroll commands, are used as MODE 
1, ITEM 1 like in the conventional types. 
However, a command for scene change which is an extension of this 
embodiment and data for improving an image quality, are provided in the 
MODE 1, ITEM 2 in a vacant region of the "R" to "W" channels. As a result, 
the softwares produced according to the signal format of this embodiment, 
are playable on the conventional playback systems, and the softwares of 
conventional signal format are playable on the playback systems of this 
embodiment, thus a two-way compatibility is achieved. 
The first and second frame memories 16 and 18 included in the memory 
section 14, are arranged to correspond with a displayed image on the 
display 26 as shown in FIG. 2A, in which pixels of 300 per line by 216 
lines are respectively laid out horizontally and vertically, and one(1) 
pixel datum is represented by a 4-bit capacity as shown in FIG. 2B. In 
this embodiment, as described before, the 2 frame memories i.e. the first 
and second frame memories 16 and 18 are provided separately, FIGS. 3A and 
3B illustrate such configuration, and in a normal operation mode to be 
explained later, each of the first and second frame memories is operated 
individually, however, in an extended operation mode which will be also 
explained later, the first and second frame memories 16 and 18 operate 
together as an integrated single unit as shown in FIG. 3C and one(1) pixel 
datum is represented by an 8-bit capacity. 
In the CLT 20, color data which can be designated by the pixel data stored 
in the first and second frame memories 16 and 18, are stored. The CLT 20 
changes its operating mode as explained before. In the extended operation 
mode, each of the pixel data is represented by 8 bits which enable a color 
representation of 2.sup.8 =256. FIGS. 4A and 4C explain this configuration 
where 8-bit color data i.e. a color number 0 to a color number 255, are 
prepared in the CLT 20 which is a combination of the first and second CLTs 
20A and 20B united to operate as a third CLT. 
As an example, a pixel datum [00000000] (not shown in FIG. 4C ) designates 
a color No. 0 which specifies RGB color element data represented as [R000, 
G000, B000], in other words, the color No. 0 to be designated by the pixel 
datum [00000000], is predetermined by a combination of [R000, G000, B000], 
the same is true to other pixel data. 
On the other hand, in the normal operation mode, one(1) pixel datum is 
represented by a 4-bit capacity as shown in FIG. 4B, thus it enables a 
color representation of 2.sup.4 =16. In this case, 16 color data of color 
No. 0 to color No. 15 shown in FIG. 4C, are prepared in CLT 20A which 
corresponds to the first frame memory 16, and another 16 color data of 
color No. 128 to Color No. 143 of FIG. 4C, are stored in CLT 20B which 
corresponds to the second frame memory 18. A relationship between a pixel 
datum and the CLT 20 for the first frame memory 16 is shown in FIG. 2B and 
FIG. 2C. 
Each of the RGB color element data (RXXX, GXXX, BXXX) can represent a 
number of bits which may be determined as desired, but in this embodiment, 
6 bits are utilized in the extended operation mode and upper 4 bits out of 
the 6 bits are utilized in the normal operation mode. 
Data value of each of the RGB color element data can be revised in response 
to the control data transmitted from a CD side, for example, [R004, G004, 
B004] may correspond to "black" or "blue", or a plurality of different 
color numbers may correspond to a same color. All of such are designated 
from the CD side. 
Data input and output to and from the memory section 14 are controlled by 
the memory controller 22, and pixel data of image, CLT data and other 
control data are obtained from the CD reproduction section by instruction 
processings of the reproduced data. Writing these data into the first and 
second frame memories 16 and 18 and the CLT 20 (20A, 20B), and reading 
4-bit or 8-bit pixel data from the first and second frame memories 16 and 
18, and reading color data corresponding to the read out pixel data from 
the CLT 20, are all controlled by the memory controller 22 based on the 
control data transmitted from the CD side. 
Output controller 24 is provided for controlling a color data output from 
the memory section 14 in response to control data, and a display 26 such 
as CRT is provided for displaying an image based on the output color data 
by being referred to the CLT 20. 
Next, operation of the embodiment of present invention will be explained. 
1. Operation of Conventional Format 
FIG. 2 illustrates how a software reproduction of conventional format is 
performed in this embodiment. The pixel data transmitted from the CD side 
are stored in the first frame memory 16 for instance, the CLT data are 
respectively stored at addresses of color numbers 0 to 15 of the CLT 20A 
for example, and the color data corresponding to the pixel data read out 
from the first frame memory 16, are read out from the CLT 20A and 
displayed on the display 26. Accordingly, an image stored in the first 
frame memory 16 is displayed in color. 
2. Operation in Normal Operation Mode 
Basic operation in the normal operation mode is similar to the above 
conventional format operation except that in this embodiment, the 
following sophisticated image processing for a scene change is possible 
because of the fact that there provided two frame memories 16 and 18 
having a capacity of 1 image (picture) each. In this case, a picture "A" 
and a picture "B" which replaces subsequently the picture "A" as the scene 
change, are preliminary stored in the first and the second frame memories 
16 and 18 respectively. In the following explanation, the scene change 
takes place from the picture "A" in the first frame memory 16 to the 
picture "B" in the second frame memory 18. 
1) CUT 
First, the picture "A" is displayed on the display 26 as such that pixel 
data stored in the first frame memory 16 are read out and inputted to the 
CLT 20A, subsequently from the CLT 20A, corresponding color data are 
outputted to the display 26 through the output controller 24. Then, upon 
receiving a [CUT] command from the CD side through the terminal 12, the 
memory controller 22 switches the first frame memory 16 to the second 
frame memory 18 concurrently with a switching of CLT 20A to CLT 20B. In 
turn, pixel data stored in the second frame memory 18 are read out and 
inputted to the CLT 20B, subsequently from the CLT 20A, corresponding 
color data are outputted to the display 26 through the output controller 
24. This results in switching quickly the picture "A" to the picture "B" 
on the screen of display 26. 
2) DISSOLVE (cross-fade) 
The picture "A" is displayed first on the display 26 in the same process as 
for the "CUT" process described before. When [DISSOLVE] commands from the 
CD side through the terminal 10 and 12 are inputted to the memory 
controller 22 and the output controller 26 and the CLTs 20A and 20B, the 
memory controller 22, in response to instructions from the CD side, 
revises color data in the CLT 20B to "black" with data sent from the CD 
side through the terminal 10 where the color data to be revised correspond 
to the picture "B" (not being displayed) of the second frame memory 18. 
Thereafter in the output controller 24, the color data read from the CLT 
20A based on the pixel data in the first frame memory 16 and the picture 
"B" of black only are added each other resulting in the picture "A" being 
displayed. 
Under this status, color data of respective color numbers defined in the 
CLT 20A, are replaced progressively from the inherent values (original 
colors) to "black" by the memory controller 22 in response to successive 
instructions given from the CD side. On the other hand in the CLT 20B, 
color data of respective color numbers are replaced progressively from 
"black" to the inherent values (original colors) by the memory control let 
22 in response to successive instructions given from the CD side. Now 
description is given to the currently displayed picture "A" of the first 
frame memory 16, when the picture "A" is dissolved in 8 increments, the 
color data in the CLT 20A is so revised that the color brightness of level 
"8" represented by the color data in the CLT 20A is decreased 
incrementally to total black as 
8.fwdarw.7.fwdarw.6.fwdarw.5.fwdarw.4.fwdarw.3.fwdarw.2.fwdarw.1.fwdarw.0, 
the color brightness of level "4", for example, is reduced to total black 
as 
4.fwdarw.4.fwdarw.3.fwdarw.3.fwdarw.2.fwdarw.2.fwdarw.1.fwdarw.1.fwdarw.0, 
the same is true to other color data. As explained above, the color data 
at their respective positions in the CLT 20A are reduced in brightness 
progressively at every increment. Accordingly, the brightness of the 
picture "A" being displayed is seemingly dimmed progressively to total 
black thus the picture "A" dissolves eventually. On the other hand, so far 
as the picture "B" is concerned, the color data revisions are implemented 
reversely to the process for the picture "A" i.e. the color data 
representing respective brightness levels are revised so that the 
brightness is progressively increased and finally all of the color data in 
the CLT 20B have their inherent color values as the picture "B" is 
displayed replacing the picture .-+.A". The above incremental picture "A" 
fade out and picture "B" fade in take place concurrently on the display 
26, during which, owing to the data capacity, the color data revision in 
the CLTs 20A and 20B is performed quicker than the pixel data revision in 
the first and second frame memories 16 and 18. 
After the aforementioned process, an output changeover is performed in the 
output controller 24 from a display status of the added picture to the 
output from the second frame memory 18 and the CLT 20B. 
It should be noted that if the pixel data in the first and second frame 
memories 16 and 18 were revised directly to attempt the above "dissolve" 
effect, it would take much more time to complete the process and during 
which unintelligible intermediate pictures would appear on the display 26. 
In contrast, revising the color data in the CLTs 20A and 20B as in the 
present invention described above enables a quick picture switching thus 
more sophisticated picture presentations are possible. 
3) EXTENDED OPERATION MODE 
In the extended operation mode, the first and second frame memories are 
combined as shown in FIG. 3C to perform as a unified unit. One pixel datum 
is now represented by an 8-bit capacity enabling an image of 256 colors by 
the CLT 20. 
As explained in the foregoing, according to the present invention, there 
provided 2 sets of frame memories (16 and 18) and the first and second 
CLTs 20A and 20B correspondingly with the 2 frame memories (16, 18), which 
are utilized effectively as such that the two frame memories (16 and 18) 
are operated individually in the normal operation mode, whereas in the 
extended operation mode, the 2 frame memories (16, 18) are operated 
together as a single unit with a third CLT (20 . . . CLT 20A combined with 
CLT 20B) in which the color data in the first CLT (20A) are held with a 
priority. This enables the compatibility with conventional systems or as 
presenting a large color variety of pictures with sophisticated image 
processings including "CUT" and "DISSOLVE" effects. 
Further, the present invention is not limited to the embodiment shown but 
following are included within the scope of the claims: 
1) Operations of the embodiment are implemented by a micro-computer. 
2) Explanation is given in an assumption that the CD-Graphics is extended 
to carry programs to be used in the present invention, but the invention 
is applicable to other image processing systems utilizing such CLTs as 
shown. 
3) Various circuit arrangements are possible as such that the CLT 20 may 
consist of 1 or more ICs, or 1 LSI (large scale IC) including other 
circuits depending on the necessity. And such as color numbers, color 
data, color values can be different from those shown in the embodiment.