JP2003163811A - Method for compressing image data, method for expanding image data, and apparatus for controlling display of image - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To save the capacity of a mask ROM and to draw an image at a high-speed. <P>SOLUTION: The image display controlling apparatus includes: the mask ROM 10 that stores compressed image data; a cell reference number storage RAM 18 (20) that stores a cell reference number of each cell of the compressed image data; expanding buffers 22, 24; and a decompression engine 26 that reads compressed image data from the mask ROM 10 and registers a cell reference number to the cell reference number storage RAM 18 (20) when information denoting presence of a reference cell exists in a header of each cell of the image data in the case of decompression or registers the cell reference number to the cell reference number storage RAM 18 (20) when no information denoting presence of the reference cell exists in the header of each cell of the image DATA, decompresses the image data in the unit of lines or dots in compliance with the data compression format of the cells and deploys the decompressed image data to the deploy buffers 22, 24. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for compressing image data such as an animation image having a relatively small number of colors, which is used in a computer game or the like by an amusement machine such as a game machine, a method for expanding the image data and image display control. Regarding the device.

[0002]

2. Description of the Related Art FIG. 9 shows a schematic structure of a main part of a conventional amusement machine such as a game machine. In the figure, an amusement machine includes a CPU 1 and an image display LSI (VDP (Video Display Processo) that performs image display processing.
r)) 2 and a ROM that stores character data
3 and a display device 4. The amusement machine having the above-mentioned configuration displays an image L under the control of the CPU 1.
SI2 reads character data from ROM3,
Processing for giving special effects such as enlargement, reduction, rotation, etc. is performed and displayed on the display device 4.

[0003]

By the way, conventional amusement machines such as game machines have been constituted by using a ROM having a small capacity and a CPU having a low clock frequency in order to reduce the price. Therefore, when it is desired to use a large number of characters in a computer game or the like, the user (the developer of the game software) needs to increase the capacity of the ROM, and the drawing speed of the amusement device is hampered by the access speed of the ROM. .

The present invention has been made in view of the above circumstances, and a method for compressing image data, a method for expanding image data, and an image display control that can save ROM capacity and perform high-speed drawing. The purpose is to provide a device.

[0005]

In order to achieve the above-mentioned object, the invention described in claim 1 is a method of compressing image data, which comprises n × m dots (n and m are both multiples of y). Image data to be divided into cells of y × y dot configuration, and each cell of the image data divided in cell units is sequentially arranged in the row direction, and corresponding dots between cells to be processed and processed cells And a cell reference compression step of separating the cells composed of the position information of the header and the reference cells and the cells composed of the header and the y × y dot data, and the header and the y × y dots. A cell consisting of data is divided into line units, and the line to be processed is 1
A line reference run that compares corresponding dots between reference lines located on a line, stores information indicating that a reference line was present when they matched, and run-length-compresses the line that does not have a reference line. And a length compression step.

The invention described in claim 2 is the same as claim 1
In the method of compressing image data according to [1], in the cell reference compression step, if the same reference cell as the processing target cell exists, the reference cell exists in the header corresponding to the target cell. When storing the information, the data of y × y dots of the target cell is not stored, the reference cell number which is the position information of the reference cell is stored, and the same cell as the target cell does not exist, The header corresponding to the cell of interest stores information indicating that the reference cell does not exist, and the data of y × y dots forming the cell of interest is temporarily stored.

The invention described in claim 3 is the same as claim 1
Or the image data compression method according to any one of 2), the line reference run length step is
If a cell with a dot structure is divided line by line and the dots between lines are compared, and the line of interest to be processed and the reference line located one line above the line of interest are the same, the line of interest Performs line reference compression by storing information indicating that the reference line exists in a header, and performs dot reference comparison within the same line with respect to a line in which no reference line exists in the line reference compression. When dots are continuous, run length compression is performed by treating them as one group.

The invention described in claim 4 is the same as claim 1
An image data decompression method for decompressing image data compressed by the image data compression method according to any one of 1 to 3, and decompressing the decompressed image data in a decompression buffer, wherein the image data is decompressed when decompressing the image data. When there is information indicating that the reference cell exists in the header of each cell, the next decompression and expansion processing is performed only by registering the cell reference number, and the information indicating that the reference cell exists in the cell header is If there is no cell reference number, the cell reference number is registered, decompression is performed in line units or dot units according to the data compression format of the cell, and the decompressed image data is expanded in the expansion buffer.

The invention described in claim 5 is the same as claim 1.
1 to 3, a first storage unit storing image data compressed by the image data compression method according to any one of 3 to 3, and a second storage unit storing a cell reference number of each cell of the data compressed image data. Means, a decompression buffer that stores image data obtained by decompressing the data-compressed image data, and a header of each cell of the image data when the data-compressed image data is read from the first storage means and decompressed. When there is information indicating that a reference cell exists, the cell reference number is registered in the second storage means, and when there is no information indicating that a reference cell exists in the header of the cell of the data compressed image data. The cell reference number is registered in the second storage means, and decompressed in line units or dot units in accordance with the data compression format of the cell, and the decompressed image is decompressed. And a control means for expanding the image data in the expansion buffer.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram showing a basic concept of a method of compressing image data according to the present invention. According to the present invention, image data is hierarchically compressed in three stages of cell reference compression, line reference compression, and run length compression (a kind of dot reference compression). Prior to cell reference compression, an image pattern composed of m × n dots (m and n are each multiples of 8) is divided into cells of 8 × 8 dot configuration shown in FIG.

First, each cell is sequentially compared in the row direction to determine whether it is the same as an adjacent cell. Where this comparison is
This is done by comparing corresponding dots between cells, and if all the corresponding dots between cells are the same, they are regarded as the same. If the same cell (reference cell) as the cell currently being processed (reference cell) exists, information indicating that the reference cell exists in the header corresponding to the focus cell and the position information of the reference cell are stored, 8x8 of the cell of interest
Dot data is not stored.

When the same cell does not exist around the cell of interest, information indicating that the reference cell does not exist is stored in the header corresponding to the cell of interest, and 8 × 8 dots forming the cell of interest are stored. The data of is temporarily stored. By the cell reference compression step of the first stage described above, each cell,
It is separated into a cell composed only of the position information of the header and the reference cell and a cell composed of the header and the dot data.

A cell in which there is no cell to be referred to in the cell reference compression, that is, a cell composed of header + dot data is a processing target in the line reference compression step which is the second stage. In the line reference compression step, cells of 8 × 8 dot configuration are divided into lines (one line is composed of 8 dots arranged horizontally), and comparison between lines is performed.

Similar to the cell reference compression, the comparison is performed by comparing the dots with each other, and if all the corresponding dots between the lines are the same, they are regarded as the same. If the line currently being processed (target line) is the same as the line located one line above the target line (reference line), the target line stores only the header indicating that the reference line exists. , 8 dots of data are not stored.

A line having no reference line in the line reference compression is a processing target in the run length compression process of the third stage. In run-length compression, dots are compared within the same line. Here, when the same dots are consecutive, the compression is performed by treating them as one group.

Next, the compression format of the image data will be described with reference to FIGS. 3 and 4. As shown in FIG. 3, the number "5" as one character is decomposed into cells each having a size of vertical and horizontal 8 × 8 dots as shown in FIG. The size of one character can be selected on a cell-by-cell basis, and if the maximum size of a character is 256 x 256 dots, the number of cells that will be decomposed vertically and horizontally will be 32. The transparent parts can be minimized.

In FIG. 3, if the row direction in the character decomposed into 32 × 32 cells is the X direction and the column direction is the Y direction and the position information of each cell is represented by coordinates (X, Y), the user can The image data of the created character is (1, 0), ..., (31, from the (0, 0) cell.
0), (0,1), (1,1), ..., (31,1), ...
......, (0,31), (1,31) ..., (31,31)
Are compressed in this order. First, as described above, it is confirmed whether or not there is the same cell as the cell of interest among the cells that have already undergone the compression processing.

When the same cell (reference cell) as the cell of interest exists, data compression is performed in the format shown in FIG. 4 (A). That is, the header (E) is set to E = 1, and after the E bit, the reference cell number that identifies the reference cell, that is, the data Y (5 bits) and X (5 bits) indicating the position information (coordinate value) of the reference cell. ) Continues. If the same cell as the cell of interest does not exist, the header (E) is set to E = 0 and the compression format inside the cell continues.

If the same cell as the cell of interest does not exist, the inside of the cell of interest is compressed line by line and dot by dot by line reference compression and run length compression. The compression format is shown in FIG. The header (Code) is represented by 4 bits and is "0x0" (0x is 16
If the header is "0x0", the variable length data portion immediately following is omitted. That is, data for eight dots in the line is not stored. When the header is "0x1" to "0x7", the run length length is -1 (2 to
8) is shown.

That is, "0x1" indicates that the same data is continuous for 2 dots, and "0x7" indicates that the same data is 8 dots.
Indicates continuous dots. The header is "0x1" to "0
In the case of x7 ", 1 byte of data follows the variable length data portion (Data) immediately after." 0x8 "to" 0x "of the header.
F "indicates the raw data length +7 (1 to 8).
"0x8" indicates that the variable length data portion immediately following is data for 1 dot (1 byte for 8 bits / dot, 4 bits for 4 bits / dot), and "0x8"
xF "is the data of 8 dots for the variable length data portion that immediately follows (8 bytes for 8 bits / dot, 4 bytes /
In the case of dots, it is 4 bytes).

Next, the character "5" drawn in the size of 256.times.256 dots shown in FIG. 3 will be specifically described. This character is assumed to be transparent except for the numeral "5". The transparent color code is set to "0". (0,
Since the cell of 0) is the first cell and there is no cell to refer to, E = 0. Then comes the compressed data inside the cell. Since the first line of the cell of (0,0) is all transparent color, "0x7" (run length 8) and "0x0" (color code 0) follow. The color code shall be allocated 4 bits / dot, that is, 4 bits per dot. Since the transparent color is the same as that of the first line from the line to the last line, "0x0" continues seven times.

The compressed codes so far are {0}, {0,
1,1,1,0,0,0,0}, {0,0,0,0},
{0,0,0,0}, {0,0,0,0}, {0,0,0,
0}, {0,0,0,0}, {0,0,0,0}, {0,0,
0,0}. In the same way, the cell of (31,0) is
Since the pattern is the same as the cell of (0,0), the position information of the reference cell (0,0) is registered with E = 1. The compression code in this case is {1, 0, 0, 0, 0, 0, 0, 0,
0,0,0}.

Continuing the work, the cells of (31, 31) are also {1, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0,0,0}. The compression code for this character is
The character data is registered in advance at a predetermined address of the mask ROM.

Next, FIG. 5 shows the configuration of the image display control device according to the embodiment of the present invention. In the figure, an image display control device according to the present embodiment is provided with a mask ROM 10 in which data compressed image data is stored and a RAM 1
4, drawing controller 16, cell reference number storage RA
M18, 20, expansion buffers 22, 24, decompression engine 26, drawing engine 28, display controller 3
0 and frame buffers 32 and 34. Three
A display device 6 is display-controlled by the image display control device.

In the mask ROM 10, the image data of each data-compressed character, that is, the above-mentioned compression code is registered in the pattern name (the start address of the memory area in which the compression code of the character is stored). . Further, the RAM 14 stores a character attribute table which is a list of attribute data of each character. As shown in FIG. 6, the character attribute table stores, for example, pattern names, palette numbers, processing data such as enlargement, reduction, and deformation, and display coordinates for each of the characters # 0 to # 256.

The drawing controller 16 controls the ROM interface 12, the decompression engine 26, and the drawing engine 28. The cell reference number storage RAMs 18 and 20 are RAMs that register cell reference numbers when decompressing compressed data. The display controller 30 reads out the image data written in the frame buffers 32 and 34 and outputs it to the display device 36.

In the above structure, when displaying an image as shown in FIG. 7 on the display device 36, the drawing controller 16 first refers to the character attribute table stored in the RAM 14 and compresses the character "5". Mask ROM that stores compressed image data (compressed code)
The pattern name in 10 is read. For example, it is assumed that the character “5” corresponds to character # 0 in the character attribute table. The drawing controller 16
RO based on the pattern name (1000H) read from character # 0 in the character attribute table
As shown in FIG. 8, the compressed code is read from the pattern name 1000H in the mask ROM 10 via the M interface 12.

The compressed code read from the mask ROM 10 is controlled by the decompression engine 26 under the control of the drawing controller 16 in accordance with the compressed data format described above.
Each dot is converted into color information and becomes image data before data compression, and this image data is expanded buffer 22.
Written in. At this time, the decompression engine 26 stores the cell reference number in the cell reference number storage RAM 18 for each cell of the character "5". If the header (E) of the cell having the character “5” is E = 1, the cell reference number that follows is registered.

In this case, since the image data of the same cell as this cell has already been written in the expansion buffer 22, only the cell reference number is stored in the cell reference number storage RAM 18, and the next cell is decompressed and expanded. Can move to work. Therefore, it is possible to shorten the time for decompressing the compressed code for this cell and expanding it into image data.

Further, when the header (E) of a certain cell in the character "5" is E = 0, the cell itself is referred to, that is, the cell position information (coordinate value) is directly used as a cell reference number for cell reference. It is stored in the number storage RAM 18. Then, it is converted into color information line by line or dot by dot in accordance with the compression format in the cell and is written in a predetermined position of the expansion buffer 22. 1 for line references
By buffering the data before the line, this data can be immediately written in the expansion buffer as the data of the corresponding line.

When the decompression of the character compression code and the expansion of the image data into the expansion buffer 22 are completed in this manner, the drawing engine 28 refers to the character attribute table stored in the RAM 14 via the drawing controller 16. The address of the expansion buffer is calculated from the cell reference number read from the cell reference number storage RAM 18 according to the attribute information such as enlargement, reduction, rotation, and deformation of the character.

While reading the color information of the character from the calculated address, drawing is performed at the address of the frame buffer 32 (or 34) corresponding to the set display position. While drawing in the frame buffer 32 (or 34), decompression and expansion processing of the next character is advanced. The display controller 30 reads the display data from the frame buffer 32 (or 34) according to the display period of the display device 36 and sends it to the display device 36.

Drawing engine 28, display controller 30
By switching the frame buffers 32 and 34 for writing and reading data in frame units, it is possible to display the image data on the display device 36 while drawing the image data in the frame buffer in real time.

[0034]

As described above, according to the present invention,
Image data composed of n × m dots (n and m are both multiples of y) is divided into cells of y × y dot configuration, and each cell of the image data divided in cell units is sequentially arranged in the row direction.
Corresponding dots are compared between the cells to be processed and the processed cells, and the cells composed of the position information of the header and the reference cell and the cells composed of the header and y × y dot data are compared. Separated from the header and y ×
A cell composed of y dots is divided line by line, and the corresponding dots between the line to be processed and the reference line located on one line are compared, and when they match, it indicates that the reference line exists. Since the information is stored in the header and the line having no reference line is run-length compressed, a mask ROM for storing character data
Capacity can be saved and the system cost can be reduced.

Further, by compressing the image data of the characters to be stored in the mask ROM, the user can store the image data of more characters in the mask ROM, so that more characters can be displayed on the display device. It becomes possible to display. Further, the influence of the access speed to the mask ROM can be suppressed.

Further, when decompressing the image data compressed by the image data compression method of the present invention and decompressing the decompressed image data in the decompression buffer, the header of each cell of the image data is decompressed. If there is information indicating that the reference cell exists, the next decompression by only registering the cell reference number, the expansion process, if there is no information indicating that the reference cell exists in the header of the cell,
The cell reference number is registered, and the decompressed image data is decompressed in the decompression buffer in line units or dot units according to the data compression format of the cell. The drawing performance can be improved.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a basic concept of a method for compressing image data according to the present invention.

FIG. 2 is an explanatory diagram showing a cell configuration when image data showing a character is decomposed into cell units.

FIG. 3 is an explanatory view showing the image data showing a character decomposed into cell units and shown together with position information.

FIG. 4 is an explanatory diagram showing a compression format used in the image data compression method according to the embodiment of the present invention.

FIG. 5 is a block diagram showing a configuration of an image display control device according to an embodiment of the present invention.

FIG. 6 is an explanatory diagram showing the contents of a character attribute table showing attribute data of each character.

7 is an explanatory diagram showing a display example of a character displayed on the display device shown in FIG.

8 is an explanatory diagram showing the stored contents of a mask ROM in the image display control device shown in FIG.

FIG. 9 is a block diagram showing a configuration of a conventional image display control device.

[Explanation of symbols]

10 ... Mask ROM, 12 ... ROM interface,
14 ... RAM, 16 ... Drawing controller, 18, 20 ...
RAM for storing cell reference numbers, 22, 24 ... Expansion buffer,
26 ... Decompression engine, 28 ... Drawing engine, 30 ... Display controller, 32, 34 ... Frame buffer, 36 ...
Display device

Continued front page    F-term (reference) 5B057 AA20 CA01 CA06 CA12 CA16                       CB01 CB06 CB12 CB18 CC01                       CG03 CG04                 5C059 KK38 LC03 MA31 MC38 ME05                       PP12 PP14 PP17 UA02 UA33                 5C078 AA01 BA44 CA01 CA27 CA34                       DA01 EA00                 5C082 AA01 AA06 BA02 BA12 BA26                       BB12 BB13 BB25 BB42 BB44                       CB05 DA13 DA42 DA73 DA86                       MM02 MM04

Claims (5)

[Claims] 1. A method of compressing image data, wherein image data composed of n × m dots (n and m are both multiples of y) is divided into cells of y × y dot structure, and divided into cell units. Sequentially in the row direction each cell of the image data
Cells corresponding to the cells to be processed and the processed cells are compared with each other, and cells composed of header and reference cell position information; and cells composed of the header and y × y dot data, And a cell reference compression step of dividing the cells composed of the header and y × y dot data into line units, and the corresponding dots between the line to be processed and the reference line located on one line are divided. Image data characterized by including a line reference run-length compression step of storing information indicating that a reference line was present in a header when compared and matched, and performing run-length compression of a line having no reference line Compression method. 2. The cell reference compressing step stores information indicating that the reference cell exists in a header corresponding to the target cell when the same reference cell as the processing target cell exists. At the same time, the reference cell number that is the position information of the reference cell is stored without storing the data of y × y dots of the target cell, and if the same cell as the target cell does not exist, it corresponds to the target cell. The information indicating that the reference cell does not exist is stored in the created header and y ×
The method for compressing image data according to claim 1, wherein data for y dots is temporarily stored. 3. The line reference run-length step divides the cells of the y × y dot configuration in line units and compares dots between lines, and a target line to be processed and its target line When the reference lines located one line above are the same, the line of interest performs line reference compression by storing information indicating that the reference line is present in the header, and the reference line is changed by the line reference compression. The run length compression is performed by comparing dots between non-existing lines within the same line, and handling the same dots as one when they are consecutive. A method for compressing the described image data. 4. An image data decompression method for decompressing image data compressed by the image data compression method according to claim 1, and decompressing the decompressed image data in a decompression buffer. If there is information that the reference cell exists in the header of each cell of the image data when decompressing, then the next decompression and expansion processing is performed by simply registering the cell reference number, and refer to the cell header. If there is no information indicating that a cell exists, register a cell reference number, decompress in line units or dot units according to the data compression format of the cell, and decompress the decompressed image data in the decompression buffer. A method of developing image data that is a feature. 5. A first storage means for storing image data compressed by the image data compression method according to claim 1, and a cell reference of each cell of the data compressed image data. A second storage means for storing a number; a decompression buffer for storing image data obtained by decompressing the data-compressed image data; a decompression buffer for reading the data-compressed image data from the first storage means; When there is information indicating that a reference cell exists in the header of each cell of the image data, the cell reference number is registered in the second storage means, and the reference cell is stored in the header of the cell of the image data that has been compressed. If there is no information to the effect that it exists, the cell reference number is registered in the second storage means, and in line or dot units according to the data compression format of the cell. And a control unit for decompressing the decompressed image data into the decompression buffer.