JP2653115B2 - Image data encoding device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image data encoding device suitable for application to a still image communication terminal.

[Summary of the Invention]

The present invention extracts a basic block including m × m (where m is a plurality) dots arranged in a matrix and including an image area of an arbitrary shape, and is configured from the extracted basic blocks. Forming a plurality of rectangular areas,
All dots between the formed plurality of rectangular areas and the image area are processed to the same ground level, and the processed plurality of rectangular areas are respectively block-coded. Thus, the efficiency of data processing and data transmission is improved.

[Conventional technology]

There is a block coding method as a coding method for compressing and coding still image data, and the block coding method includes an ABTC (Adaptive Block Truncation Coding:
Adaptive block truncation coding, ADCT (Adaptive Discrete Cosin Trunc)
ation: adaptive discrete cosine truncation).

For example, according to the block coding method of the ABTC method, image data of a still image composed of 768 × 480 pixels in the horizontal and vertical directions on the screen of a cathode ray tube of a monitor receiver is block-coded. Sets a basic block composed of 8 × 8 dots (dot data) arranged in a matrix, and 768 × 4 dots arranged in a matrix.
Eighty dots are divided into 96 × 60 basic blocks arranged in a matrix, and each basic block is encoded. Also, a 1/4 block composed of 4 × 4 dots and a 1/4 block composed of 2 × 2 dots are arranged in a matrix.
/ 16 block is set, and the basic block is divided into four quarter blocks depending on the contents of the dots constituting the basic block (contents of dot data), and each is coded. Depending on the content of the dot in the block,
The 1/4 block is further divided into four 1/16 blocks for encoding.

If the image data of the still image is a monochrome signal, the above-described encoding process is performed as it is. If the image data is a color signal, a luminance signal, two color difference signals, or 3
The above-described encoding process is performed for each of the primary color signals.

The block-coded image data is transmitted together with the data of the coordinates X and Y of a set of diagonal points (start point and end point) of each basic block. In this case, in the case of rectangular area image data composed of a plurality of basic blocks, data of the coordinates X and Y of a pair of diagonal points of the rectangular form may be transmitted together with the rectangular area image data. It is not necessary to transmit the data of the coordinates X and Y of each set of diagonal points for each of the basic blocks constituting, so that the data processing and transmission become easy.

[Problems to be solved by the invention]

A reference example in a case where an image area having an arbitrary shape is subjected to block coding will be described with reference to FIG. In a still image communication terminal, a matrix stored in a memory (video RAM) corresponding to each pixel of a screen composed of, for example, 768 × 480 pixels in the horizontal and vertical directions on the surface of a cathode ray tube of a monitor receiver. An X, Y orthogonal coordinate system with an origin O at the upper left corner of the screen is set for image data of a still image composed of 768 × 480 dots (dot data)
The axis will be scaled from 0 to 768, and the Y axis will be scaled from 0 to 480. In FIG. 4, only a portion near the origin O of the X, Y coordinate system is shown. Then, the above-mentioned 768 × 480 dots are located at the respective intersections of straight lines extending at right angles from the X and Y axes for each scale.

Here, BL indicates a basic block, and is composed of 8 × 8 dots (dot data) arranged in a matrix.
And this screen is 96 × 60 arranged in a matrix
It is composed of basic blocks BL.

IR indicates an image area to be block-coded, and is a case where the contour shape is a triangle (ΔACE) as an example. Consider a case where such an image area IR is subjected to block coding. That is, a short area RR ₀ (□ ABCD) including the image area IR is formed, and all dots between the short area RR ₀ and the image area IR are set to the same ground level (background level). For example, a black level (minimum level) is set.

Then, such a rectangle area RR _0, the block encoding means ABTC scheme and block coding. And
The image data of the still image is divided into 96 basic blocks in the first row from left to right, 96 basic blocks in the second row from left to right,. The basic blocks are coded from left to right, and the 96 basic blocks in the 60th row are coded from left to right for each basic block. Also, 1/4 blocks and 4 × 4 dots each consisting of 4 × 4 dots arranged in a matrix form
× 1/16 block consisting of 2 dots is set, and the contents of the dots that make up the basic block (contents of dot data)
In some cases, the basic block is divided into four quarter blocks and each is encoded, and depending on the contents of the dots in the quarter block, the quarter block is further divided into four 1/1
It is divided into six blocks and encoded. If the level of all 8 × 8 dots in the basic block is the ground level (for example, black level) or another level, the level is set as the block coded data of the basic block. Since it is sufficient to use data, the compression rate of data by block coding becomes the best.

In the case of rectangle area RR _0, the block coded data for each basic block constituting it, rectangle area RR
A pair of diagonal points of ₀ , that is, a point closer to the origin O, that is, a start point A and a point farther, that is, data of each coordinate X, Y of an end point C, together with the communication processing circuit of the still image terminal and The signal is supplied to the interface and modulated, and a necessary synchronization signal or the like is added to the signal and transmitted to the transmission line.

In this manner, when the image area IR having an arbitrary shape is subjected to block coding, one short area RR ₀ including the image area IR is included.
When forming a, the starting point A and the coordinates X of the end point C of rectangle area RR _0, it may be transmitted to data of Y, the starting point of each basic block BL constituting the rectangle area RR ₀ and Since it is not necessary to transmit the data of the coordinates X and Y of the end point,
While data processing and transmission is made easier, since rectangle area including an image area IR is one, the same land between the rectangle area RR ₀ and the image area IR level (level of the background), For example, since the number of dots at the black level (minimum level) is large, there are drawbacks that it takes a long processing time and transmission efficiency is poor.

In view of the above, an object of the present invention is to propose an image data encoding device that increases the efficiency of data processing and data transmission.

[Slack means to solve the problem]

According to the present invention, there is provided an extracting means for extracting a plurality of basic blocks each composed of m × m (where m is a plurality) dots arranged in a matrix, and two diagonal points each of an image area having an arbitrary shape. The size, position and number are determined so as to be located on the contour line and to include all the image areas of an arbitrary shape, and form a plurality of rectangular areas each composed of a plurality of basic blocks. Forming means, processing means for setting a signal level of a dot located outside an image area of an arbitrary shape among dots in a plurality of rectangular areas to a black level, and a plurality of rectangular shapes processed by the processing means An image data encoding apparatus comprising: a block encoding unit that encodes data in an area in units of blocks.

[Action]

According to the present invention, a plurality of basic blocks each composed of m × m (where m is a plurality) dots arranged in a matrix are extracted by the extracting means, and two diagonal points are formed by the forming means. Are located on the contour line of the image area of an arbitrary shape, and the size, position and number are determined so as to include all of the image area of the arbitrary shape. A plurality of rectangular areas are formed, and the signal level of the dots located outside the image area of an arbitrary shape among the dots in the plural rectangular areas is set to the black level by the processing means, and the block coding means , The data in the plurality of rectangular areas processed by the processing means are encoded in block units.

〔Example〕

Hereinafter, an embodiment in which the image data encoding apparatus of the present invention is applied to a still image communication terminal will be described with reference to FIG. (1) Computer (microcomputer)
CPU (Central Processing Unit) (2), ROM (3) and RAM
It consists of (4). (5) bus of CPU (2) (consisting of data bus, address bus, control bus, etc.)
The ROM (3) and the RAM (4) are connected to the bus (5). The computer (1) controls each unit of the still image communication terminal.

(13) is a transmission line, which can be wireless or wired,
For the wired transmission path, ISDN (Integrated Services Digital Network), high-speed digital line, analog telephone line, DDX (Digital Data Exchange Network (there are two types, DDXC and DDXP), A dedicated line or the like is possible.

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

(6) is a frame memory (video RAM) whose digital video signal input / output terminal and control signal input terminal are connected to the bus (5), and whose digital video signal input terminal is A / A.
The digital video signal output terminal is connected to the input terminal of the D / A converter (7), and the other control signal input terminal is connected to the display timing control circuit ( 11) Connected to the output terminal. The writing and reading of the memory (6) are controlled by the computer (1) and the display control circuit (11). The memory (6) includes a horizontal and vertical address counter, a memory controller and the like.

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

The digital video signal read 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) having a cathode ray tube and projected on the surface 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 into a digital video signal, and then supplied to the memory (6). The image data is written as still image data. The image data written in the memory (6) is encoded by the computer (1), and coordinate data of a pair of diagonal points of each basic block or In the case of a plurality of rectangular areas including a plurality of the basic blocks, the rectangular blocks are supplied to the communication processing circuit and the interface (12) together with the coordinate data of the set of diagonal points of the rectangular blocks and subjected to the communication processing. Is transmitted to another still image communication terminal through the transmission line (13).

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

As shown in FIG. 2, the memory (6) is stored in the memory (6) corresponding to each pixel of a screen composed of, for example, 768 × 480 pixels in the horizontal and vertical directions on the surface of the cathode ray tube of the monitor receiver (8). Image data of 768 x 480 dots (dot data) arranged in a matrix
Set an X, Y rectangular coordinate system with the origin O at the upper left corner of the screen, with 0 to 768 as the scale on the X axis and 0 to 480 as the scale on the Y axis. It becomes.
FIG. 2 shows only a portion near the origin O of the X, Y coordinate system. Then, each one at right angles from the X and Y axes
The above-mentioned 768 × 480 dots are positioned at each intersection of a straight line extended for each scale.

Here, BL indicates a basic block and is composed of 8 × 8 dots (dot data) arranged in a matrix.
And this screen is 96 × 60 arranged in a matrix
It is composed of basic blocks BL.

In FIG. 2, IR indicates an image area IR having an arbitrary shape, and here, the same triangle (ΔAC) as in FIG.
E).

Now, referring to FIG. 1, the extraction unit extracts a basic block BL including 8 × 8 dots arranged in a matrix and including an image area IR of an arbitrary shape (step ST-1). ).

Next, the basic block extracted by the forming means
From BL, a plurality of, for example, five rectangular areas RR _{0 to} RR ₅ (□
A ₁ B ₁ C ₁ D ₁ , A ₂ B ₂ C ₂ D ₂ , A ₃ B ₃ C ₃ D 3, A ₄ B ₄ C ₄ D ₄ , A ₅
B ₅ C ₅ D ₅₎ to form a (step ST-2). These rectangle area RR ₀ ~RR _5, the number of dots between each rectangular area and the image area IR is formed in such a way that minimized.

Next, five short areas RR ₀ -R
The level of all dots (dot data) between the R ₅ and the image area IR, the same land of level (level of the background), for example, to a black level (lowest level).

Then, the block encoding means ABTC scheme, a rectangular area RR ₀ ~RR _{5 5} amino which is this process, respectively block coding. Then, the image data of the still image is
The 96 basic blocks in the first row are arranged from left to right,
Number of basic blocks from left to right, ..., 96 in line 59
The basic blocks are coded from left to right, and the 96 basic blocks in row 60 are coded from left to right for each basic block.
Also, a 1/4 block composed of 4 × 4 dots and a 1/16 block composed of 2 × 2 dots are arranged in a matrix.
Depending on the content of the dots (contents of the dot data) constituting the basic block, the basic block is divided into four quarter blocks, and each is encoded.
Also, depending on the contents of the 1/4 block dot,
The / 4 block is further divided into four 1/16 blocks for encoding. If the level of all 8 × 8 dots in the basic block is the ground level (for example, black level) or another level, the level is set as the block coded data of the basic block. Since it is sufficient to use data, the compression rate of data by block coding becomes the best.

Then, in the case of the rectangular area RR ₀ ~RR _5, the block coded data for each basic block constituting it, the start and end points of the rectangular area _{RR 0 ~RR 5 A 1, C} 1; A 2 , C ₂ ; A ₃ ,
C ₃ ; A ₄ , C ₄ ; A ₅ , C ₅ The data of the respective coordinates X and Y are supplied to the communication processing circuit and the interface (12) through the bus (5) in FIG. A necessary synchronization signal or the like is added and transmitted to the transmission line (13).

In this case, as the number of rectangular areas formed by combining the basic blocks BL including the image areas IR increases, the number of dots between the plurality of rectangular areas and the image areas IR decreases. Instead, since the number of data of the coordinates X and Y of the start point and end point of the rectangular area increases, the number, position,
Select the shape, etc.

According to the image data encoding apparatus described above, a matrix of 8 pixels including an image area of an arbitrary shape is included.
A basic block BL composed of × 8 dots is extracted, a plurality of rectangular areas RR _{0 to} RR ₅ composed of the extracted basic blocks BL are formed, and a plurality of rectangular areas formed are formed. RR ₀ ~RR ₅ and the total dot between the image area image area IR, and the level of the same land, by the processed plurality of the rectangle area was set to respectively block encoding, a data processing And the efficiency of data transmission is increased.

〔The invention's effect〕

According to the present invention described above, it is possible to obtain an image data encoding device that can increase the efficiency of data processing and data transmission.

[Brief description of the drawings]

1 is a flowchart of an embodiment of the present invention, FIG. 2 is an explanatory diagram of the embodiment, FIG. 3 is a circuit diagram of the embodiment, and FIG. 4 is an explanatory diagram of a reference example. (1) computer, (2) CPU, (3) ROM,
(4) RAM, (5) bus, (6) 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, BL is a basic block, and IR is an image area. , RR ₀ ~RR ₅ is a short form area.

Claims (1)

(57) [Claims] 1. An extracting means for extracting a plurality of basic blocks each comprising m × m (where m is a plurality) dots arranged in a matrix, and an image area having two diagonal points each having an arbitrary shape. The size, position, and number are determined so as to be located on the contour line and including all of the image area having the arbitrary shape, and a plurality of rectangular areas each including the plurality of blocks are defined. Forming means for forming; processing means for setting a signal level of a dot located outside the image area of an arbitrary shape among the dots in the plurality of rectangular areas to a black level; A block encoding means for encoding data in the plurality of rectangular areas in units of blocks.