JPH0236670A - Coder for picture data - Google Patents

Abstract

PURPOSE:To attain block coding to a rectangular picture data with more fidelity by processing all dots between an expanded area and a picture area so as to be in the same background level and applying block coding the extended area including the picture area. CONSTITUTION:A rectangular extended area ER is set, which includes a rectangular picture area IR and consists of plural basic blocks BL comprising mXm (where m is a plural number) sets of dots DT arranged as a matrix. Then the processing is applied in a way that all dots DT between the extended area ER and the picture area IR are in the same background level and the extended area subjected to the said processing and including the picture area IR is block- coded. Thus, the rectangular picture data is block-coded with much fidelity.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image data encoding device suitable for use in still image communication terminals.

[Summary of the invention]

The present invention sets a rectangular enlarged area made up of a plurality of basic blocks made up of m×m (where m is plural) dots arranged in a matrix and includes a rectangular image area, and expands the rectangular enlarged area. All dots between the areas and the image area are processed to be on the same ground level, and the processed enlarged area including the image area is block encoded, thereby converting rectangular image data. This allows more faithful block encoding.

[Conventional technology]

There is a block encoding method as an encoding method for compressing and encoding still image image data.
Truncation Coding: Adaptive
block truncation coding method, A
DCT (Adaptive Discrete Co5
1ne Truncation (adaptive discrete cosine truncation) method, etc.

For example, using the ABTC block coding method,
For example, in order to block encode still image data on the tube surface of a cathode ray tube of a monitor receiver, which consists of 768 x 480 pixels in the horizontal and vertical directions, 8 x 8 pixels arranged in a matrix are required. A basic program consisting of dots (dot data) is set, and the 768 x 480 dots arranged in a matrix are divided into 96 x 60 basic blocks arranged in a matrix, and each basic block is encoded. do. In addition, 1/4 block and 2
A 1/16 block consisting of ×2 dots is set, and depending on the contents of the dots that make up the basic block (contents of dot data), the basic block is divided into four 1/4 blocks, each of which is coded. Then, depending on the content of the dots in the 1/4 block, the 1/4 block is further divided into four 1/16 blocks for encoding.

Note that if the image data of a still image is a monochrome signal, the above-mentioned encoding process is performed immediately; if it is a color signal, it is encoded for each luminance signal, every two color difference signals, or every three primary color signals. The above-mentioned encoding process is then performed.

Further, the block-encoded image data is transmitted together with data on the coordinates X and Y of a set of diagonal points (starting point and ending point) of each basic block. In this case, in the case of rectangular area image data consisting of a plurality of basic blocks, it is sufficient to transmit the data of the coordinates X and Y of a pair of diagonal points of the rectangle together with this data, which constitutes the area of the rectangle. Since it is not necessary to transmit the data of the coordinates X and Y of each pair of diagonal points for each basic program, processing and transmission of the data is facilitated.

[Problem to be solved by the invention]

By the way, the rectangular image area to be encoded is 1
There is no problem if the image area is composed of one or more basic blocks, but if part of the image area is included in the basic block, conventionally, the image area is not included. The above-mentioned block encoding process was performed after assuming that the entire basic block was included in the image area, or that the basic block was not included in the image area at all. So,
It was not possible to faithfully block encode the image area.

In light of this problem, the present invention seeks to propose an image data encoding device that can more faithfully block encode rectangular image data.

[Means to solve the problem]

The present invention is an enlarged area setting that sets a rectangular enlarged area that includes a rectangular image area and is made up of a plurality of basic blocks made up of m×m (where m is plural) dots arranged in a matrix. means (ST-1 to ST-4), a processing means (ST-5) for making all dots between the enlarged area and the image area at the same ground level, and a processed enlargement including the image area; It has block encoding means (ST-6) for block encoding an area.

[Effect]

According to the present invention described above, a rectangular image area is arranged in a matrix of m×m (where m is plural).
A rectangular enlarged area made up of a plurality of basic blocks made up of dots is set, and all dots between the enlarged area and the image area are processed to be on the same ground level, and the processed The enlarged area (including the image area) is block encoded.

〔Example〕

An embodiment in which the image data encoding device of the present invention is applied to a still image communication terminal will be described below with reference to FIG. (1) is a computer (microcomputer),
It consists of CPU (central processing unit) (2), ROM (3) and RAM (4). (5) is the CPU
In the bus (2) (consisting of data bus, address bus, control bus, etc.), ROM (3) and RAM (4) are
It is connected to this path (5). This computer (1) controls each part of this still image communication terminal.

(13) is a transmission line, which can be wireless or wired,
In the case of wired transmission lines, these include 15DN (Ingrated Services Digital Network), high-speed digital lines, analog telephone lines, and DDX (digital data exchange networks).
There are two types of DXP), a dedicated line, etc.

(12) is a communication processing circuit and an interface connected between the transmission line (13) and the path (5) according to the protocol and transmission speed of the still image signal of the transmission line (13); The communication processing circuit performs transmission processing and reception processing, such as encoding and modulation for transmission, and decoding and demodulation for reception, respectively.

(6) is a frame memory (video RAM) whose digital video signal input/output terminal and control signal input terminal are connected to path (5). The digital video signal input terminal is connected to the output terminal of the A/D converter (10), the digital video signal output terminal is connected to the input terminal of the D/A converter (7), and the other control A signal input terminal is connected to an output terminal of a display timing control circuit (11).

The writing and reading of this memory (6) is controlled by the computer (1) and the display control circuit (11). Note that this memory (6) includes horizontal and vertical address counters, a memory controller, etc.

(9) is an analog video signal input terminal, and the video signal from this input terminal (9) (video signal from a video camera, VTR, etc.) is supplied to the A/D converter (10) and converted into a digital video signal. After being converted, it is supplied to the memory (6) and written therein.

The digital video signal read out from the memory (6) is
After being supplied to a D/A converter (7) and converted into an analog video signal, it is supplied to a monitor receiver (8) equipped with a cathode ray tube and displayed on the screen of the cathode ray tube.

As described above, the analog video signal supplied to the input terminal (9) is supplied to the A/D converter (10), converted to a digital video signal, and then supplied to the memory (6). The image data written in the memory (6) is encoded by the computer (1) and converted into coordinate data of one set of diagonal points of each basic block. Or in the case of a rectangle containing multiple basic blocks, one of the rectangles
After being supplied to the communication processing circuit and interface (12) together with the coordinate data of the diagonal points of the set and subjected to communication processing,
It is transmitted to other still image communication terminals through the transmission line (13).

Next, encoding of image data stored in the memory (6) will be explained with reference to the flowchart of FIG. 1 and the explanatory diagram of FIG. 2. Note that the block encoding here employs the well-known ABTC method mentioned at the beginning.

As shown in FIG. 2, a memory (6) is provided corresponding to each pixel of a screen consisting of, for example, 768 x 480 pixels in the horizontal and vertical directions on the surface of the cathode ray tube of the monitor receiver (8).
768X480 arranged in a matrix stored in
Dots (dot data) For still image data consisting of DT,
, the Y orthogonal coordinate system is set, and the X axis has a scale from 0 to 7.
Numbers up to 68 will be assigned, and numbers from O to 480 will be assigned as a scale on the Y axis. In addition, in Figure 2, the X,
Only the portion close to the origin O of the Y coordinate system is shown. Then, the above-mentioned 768×480 dots DT are positioned at each intersection of straight lines extending perpendicularly from the X and Y axes for each scale.

Here, BL indicates a basic block, which is composed of 8×8 dots (dot data) DT arranged in a matrix. And this screen consists of 9
It is composed of 6×60 basic blocks BL.

In this Figure 2, IR is a rectangular image area, and here there are a pair of diagonal points, namely a point A that is closer to the origin O (this is taken as the starting point) and a point that is farther away (this is taken as the ending point). ) B
For example, (12, 13), (26
, 27).

Now, referring to FIG. 1, the determining means determines whether or not the coordinates X and Y of the starting point A of the image area IR are both multiples of 8 (step ST-1). If YES, the process moves to step 5T-3. Here, the coordinates of starting point A are X, Y
The fact that both are multiples of 8 means that the starting point A coincides with the starting point of any of the basic blocks. Therefore, the determination in step ST-1 is to determine whether the starting point A of the image area IR coincides with the starting point of any basic block.

In the example of FIG. 2, since the determination result in step ST-1 is No, the process moves to step 5T-2. In step 5T-2, the calculation means sets the coordinate X70 point obtained by rounding down the fractions of the coordinates X and Y of the starting point A of the image area IR that are not multiples of 8 as the new starting point a. Second
In the example shown, the coordinates X, Y of the starting point A of the image area IR are (12, 13), so if the fractions of each coordinate that are not multiples of 8 are rounded down, the coordinates X, Y are (8, 8
), and the new starting point a of these coordinates coincides with the starting point of the nearest basic block outside the starting point A of the image area IR.

Referring again to FIG. 1, after step 5T-2,
The process moves on to step 5T-3, and in step 5T-3, the determining means determines that the coordinates X of the end point B of the image area IR,
It is determined whether Y is a multiple of 8 or not. If YES, the process moves to step 5T-5. Here, the coordinates X of the end point B,
The fact that both Y are multiples of 8 means that the end point B coincides with any end point of the basic block. Therefore, the determination in step 5T-3 is to determine whether the end point B of the image area IR coincides with the start point of any basic block.

In the example of FIG. 2, the determination result in step 5T-3 is No, so the process moves to step 5T-4. In step 5T-4, the arithmetic means calculates the coordinate X of the end point B of the image area IR by rounding down fractions of the coordinates X and Y that are not multiples of 8.

Let point Y be the new end point. In the example in Fig. 2, the coordinates X, Y of the end point B of the image area IR are (26, 27), so if each coordinate that is not a multiple of 8 is rounded up, the coordinates X, Y are ( 32, 32) The new end point of this coordinate is outside the end point B of the image area IR and coincides with the end point of the nearest basic block.

In this way, an enlarged area ER consisting of nine basic blocks is set, which is determined by the new starting point a and the new ending point.

Then, the determination means in steps ST-1 and ST-3 and the calculation means in steps ST-2 and ST-4 determine a plurality of basic blocks consisting of 8×8 dots arranged in a matrix and including a rectangular image area. An enlarged area setting means is configured to set a rectangular enlarged area ER consisting of.

After step 5T-4, proceed to step 5T-5,
In step 5T-5, the data processing means calculates all dots (dot data) between the rectangular enlarged area ER determined by the new start point a and the new end point and the image area IR.
to the same ground level (background level), for example, the black level (lowest level).

After step 5T-5, proceed to step 5T-6,
In step 5T-6, the enlarged area ER is block encoded by the ABTC block encoding means. Then, the image data of the still image is stored at 96 in the first row.
96 basic blocks in the 2nd row from left to right, 96 basic blocks in the 59th row from left to right, 96 in the 60th row The basic blocks are encoded one by one from left to right.

In addition, a 1/4 block consisting of 4 x 4 dots arranged in a matrix and a 1/4 block consisting of 2 x 2 dots are arranged in a matrix.
/16 blocks are set, and depending on the content of the dots that make up the basic block (the content of dot data), the basic block is divided into four 1/4 blocks and each is encoded. Depending on the content of the dots in a block, the 1/4 block is further divided into four 1/16 blocks for encoding. In addition, if the level of all 8×8 dots in a basic block is the ground level (for example, black level) or another level, that level is used as the block encoded data of that basic block. Since it can be used as data, the compression rate of data by block encoding is the best.

In the case of a rectangular enlarged area ER, the block encoded data for each basic block constituting the enlarged area ER is stored together with the data of the coordinates X and Y of the starting point a and the ending point of the enlarged area ER, and When the enlarged area ER consists of one basic block, the block encoded data of that basic block is transferred to the bus shown in FIG. Through (5), the signal is supplied to the communication processing circuit and interface (12), modulated, added with necessary synchronization signals, etc., and sent out on the transmission line (13).

According to the image data encoding device described above, a rectangular enlarged area ER including a rectangular image area IR and consisting of a plurality of basic blocks BL is set, and the enlarged area E is
All dots DT between R and image area IR are processed to have the same ground level, for example, black level, and the processed enlarged area ER including image area IR is block encoded. This allows rectangular image data to be block encoded more faithfully.

〔Effect of the invention〕

According to the present invention described above, rectangular image data can be more faithfully block encoded.

[Brief explanation of the drawing]

FIG. 1 is a flowchart of an embodiment of the present invention, FIG. 2 is an explanatory diagram of the embodiment, and FIG. 3 is a block diagram showing a circuit of the embodiment. (1) is computer, (2) is CPU, (3) is RO
M, (4) is RAM, (5) is bus, (6) is memory,
(7) is a D/A converter, (8) is a monitor receiver, (9)
is an input terminal, (10) is an A/D converter, (11) is a display timing control circuit, DT is a dot, BL is a basic block, IR is an image area, and A and B are image areas Il', respectively.
The start and end points of l, BL are the enlarged area, and a, b are the new start and end points of the enlarged area ER, respectively.

Claims (1)

[Claims] an enlarged area setting means for setting a rectangular enlarged area made up of a plurality of basic blocks made up of m×m (where m is plural) dots arranged in a matrix, which includes a rectangular image area; The present invention further comprises processing means for making all dots between the enlarged area and the image area at the same ground level, and block encoding means for block coding the processed enlarged area including the image area. An image data encoding device characterized by: