JPH08116545A - Image transmission method and system therefor - Google Patents

Abstract

PURPOSE: To reduce a transmission quantity of image data with simple configuration by transferring an address change and difference data so as to eliminate the need for discrimination and processing of a dynamic image part and a still image part. CONSTITUTION: In the system in which an image changing on time base is divided into unit image layer blocks and the resulting block is sent, a transfer side stores image data before and after an original image in an image memory 1 with respect to a time base of the image block are stored in memories 3, 4, and a differential arithmetic unit 5 calculates a difference from a change in succeeding and preceding data and the result is transferred. Simultaneously an address change decision circuit 2 transfers an address change to a receiver side address read circuit 10. A memory 6 stores once transfer data in the receiver side and data of the same block in an image memory 9 storing preceding image information are read from a memory 8 by the address read circuit 10 and a decoding computing element 7 applies inverse conversion to the data to rewrite the content of the memory 9. Thus, excellent image transmission is made by having only to transfer the address change and the difference data.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image transmission method and an image transmission system, and more particularly to a moving image transmission method in digital image transmission.

[0002]

2. Description of the Related Art Various compression techniques have been proposed for conventional image transmission methods, particularly for moving image transmission. For example, MPEG (MOVING PICTURE EX)
The PERT GROUP) method is one of them.

Further, Japanese Patent Laid-Open No. 59-152785,
As disclosed in Japanese Patent Application Laid-Open No. 62-24787, one screen is divided into a plurality of blocks, and the information about the difference between frames is transmitted in each block to reduce the transmission amount. Has been.

[0004]

However, in the conventional image transmission methods as described in the above publications,
Since it is premised on transmitting high-quality moving images,
It required a lot of processing to judge and compare the moving image part and the still image part.

Therefore, if these image transmission methods are used, the determination circuit and the signal processing circuit become complicated, and there is a problem that the device configuration becomes large. SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to enable a device having a relatively simple structure to reduce the amount of image data transmitted.

[0006]

In order to achieve the above object, the image transmission method of the present invention divides an image changing on the time axis into unit image blocks represented by N × M pixels. In the image transmission method of transmitting, one moving direction code selected from nine moving direction codes at the same position indicating the moving direction of pixels, up and down, left and right, and diagonally up, down, left and right, and difference data between data before and after moving are provided for each pixel. It is transmitted every time.

Another feature of the image transmission method of the present invention is that the moving direction code is difference data between an address ahead of the moving direction and an address before moving in the unit image block. There is.

Further, the image transmission system of the present invention is an image transmission system in which an image changing on a time axis is divided into unit image blocks represented by N × M pixels and transmitted. The transmission side includes an address change value determination circuit that determines a change value of an address of a pixel and a difference calculator that calculates a difference data value of data before and after movement in each pixel, and the address change value determination circuit and the difference calculation While sending the value respectively obtained by the device to the receiving side, based on the address determined by the address change value determining circuit, an address reading circuit for reading the data value before the movement from the image memory of the receiving side, From the difference data value calculated by the difference calculator on the transmitting side and the data value before movement read by the address reading circuit Decoding the data receiving-side apparatus and a decoding arithmetic to be stored in the image memory is characterized by including.

[0009]

Since the present invention comprises the above technical means, the receiving side device simply adds the moving direction code sent from the transmitting side device to the address of the pixel to be decoded and obtains the data of the address. The target image data can be decoded by adding the difference data to the image data, and the transmission amount of the image data can be reduced with a simple circuit configuration.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the image transmission method and image transmission system of the present invention will be described below with reference to the drawings. 1 is a block diagram showing a schematic configuration of an image transmission system of the present invention, FIG. 2 is a diagram showing a first transfer image and a stored structure, and FIG. 3 is a diagram explaining a second transfer image. Four
FIG. 6 is a diagram for explaining an address change due to image movement. Note that, here, a case where the data to be transferred is 8 bits per word will be described.

In FIG. 1, the left side of the dotted line shows the configuration of the transfer side, the right side of the dotted line shows the configuration of the receiving side, and the original image to be transferred is stored in the image memory 1. And
Transfer data is subjected to transfer processing block by block as shown in FIG.

Further, the memories 3 and 4 temporarily store the image data before and after each block on the time axis, and when these image data are given to the difference calculator 5, the change in the data before and after is performed. The difference is calculated.

On the other hand, on the receiving side, the transmitted data is temporarily stored in the memory 6. Then, the data of the same block stored in the image memory 9 in which the information of the previous screen is stored is read into the memory 8. Then, the read image data is inversely converted by the decoding arithmetic unit 7, and the contents of the image memory 9 are rewritten with the result.

FIG. 2A shows a part of the first transfer image, which is stored in the image memory 1 at the address shown in FIG. 2B. FIG. 3 (a) is shown in FIG.
It is a part of the second image in the same place as. in this case,
It is considered that the image is moving diagonally upward to the right as compared with the previous image. Therefore, the image is divided into n pieces according to the change and transferred.

When the image is transferred in this way, in this embodiment, the operation is performed on the address where the previous image is stored by the moving position from the previous image (8 positions as shown in FIG. 4). The difference data from the previous data stored in the memory 4 is transferred.

On the receiving side, it is temporarily stored in the memory 6, inversely transformed by the decoding arithmetic unit 7, and then stored in the image memory 9. This is repeated for the number of divisions and the next screen is transferred.

Here, a specific example will be described. First, the first screen of FIG. 2 (a) is transferred, and the data is stored as shown in FIG. 2 (b). Then, on the next screen, the screen is divided into n pieces according to the size of the movement of the image, and one divided screen is assumed to be FIG. In this case, the image has moved diagonally to the right above the previous image.

At this time, the image moved to the address ((address value where the previous image is stored) +7) of the previous image is stored. For example, B5 of the current data in FIG.
(Address value: 12) is C4 of the previous data in FIG.
(Address value: 19) has moved.

Also, C4 of the current data (address value: 1
In 9), D3 of the previous data (not shown, the address value in this case is 26) has moved.
However, it can be considered that the values are not exactly the same as the previous data, even though they have actually moved in the image.

Therefore, the difference data with the value after the movement is actually transferred. In this case, in order to reproduce the address value of the current data: 12 (B5, data value: 163) on the receiving side, the address value of the previous data: 12 + 7 = 19 (C
4. Difference from data value: 160): <163 (read to memory 3) -160 (read to memory 4)> is calculated by the difference calculator 5, and the calculation result “+3” is received. Transfer to the side.

The difference data "+3" thus sent is transferred to the memory 6 on the receiving side. On the other hand, the address change value determination circuit 2 on the transmission side sends the address change value to the address read circuit 10 on the transmission side, and the address read circuit 10 reads the value 160 of the previous data to the memory 8.

As a result, the decoding arithmetic unit 7 performs an operation based on the value held in the memory 6 and the value held in the memory 8 to obtain the data value: 163. The number of bits of the difference data at this time is about 5 bits, and 00000 to 11110 is set to be normal.

If the difference data is 5 bits or more, the difference data is transferred after 11111. While performing these processes for each divided screen, image transfer is sequentially performed so as to execute data transfer.

According to the above method, a predetermined image can be decoded on the receiving side by transferring only the address change value and the difference data from the transmitting side, and the transfer data amount can be reduced with a simple circuit configuration. Can be significantly reduced.

[0025]

Since the present invention is constructed as described above,
According to the present invention, good image transmission can be performed only by transferring the address change value and the difference data.
As a result, it is possible to reduce the amount of image data transmitted with a simple circuit configuration, and it is possible to favorably realize both the simplification of the configuration of the image transmission system and the reduction of the amount of image data transmission. it can.

[Brief description of drawings]

FIG. 1 is a block diagram illustrating an example of a device configuration of a system that implements an image transmission method according to an embodiment.

FIG. 2 is a diagram for explaining a first transfer image and a storage structure according to an embodiment of the present invention.

FIG. 3 is a diagram illustrating a second transfer image according to the embodiment.

FIG. 4 is a diagram showing address change values with respect to movement of an image.

[Explanation of symbols]

 1 image memory 2 address change value determination circuit 3 transmission side memory 4 transmission side memory 5 difference calculator 6 reception side memory 7 decoding calculator 8 reception side memory 9 image memory 10 address read circuit

Claims (3)

[Claims] 1. An image transmission method for transmitting an image that changes on the time axis by dividing it into unit image blocks represented by N × M pixels, the same position indicating the moving direction of pixels, and vertical and horizontal directions and diagonal directions. An image transmission method characterized in that one movement direction code selected from a total of nine movement direction codes of up, down, left and right and difference data of data before and after movement are transmitted for each pixel. 2. The image transmission method according to claim 1, wherein the movement direction code is difference data between an address before a movement direction and an address before a movement in the unit image block. . 3. An image transmission system in which an image changing on a time axis is divided into unit image blocks represented by N × M pixels and transmitted, and a change value of an address of each pixel is determined. The address change value determining circuit and the difference calculator for calculating the difference data value of the data before and after the movement in each pixel are provided in the device on the transmission side, and are calculated by the address change value determining circuit and the difference calculator, respectively. And the difference between the address reading circuit that reads the data value before the movement from the image memory on the receiving side based on the address determined by the address change value determining circuit and the transmitting side. The current data is decoded from the difference data value calculated by the calculator and the data value before movement read by the address reading circuit, and the reception is performed. An image transmission system, characterized in that the device on the receiving side and a decoding arithmetic to be stored in the image memory is provided.