JPS62248393A - Picture signal transmission system - Google Patents

Abstract

PURPOSE:To obtain a smooth reproducing moving image having an improved visual characteristic by dividing both surfaces into plural areas, applying priority to the respective areas and transmitting more information of the area of the higher priority than the information of the area of the lower priority. CONSTITUTION:The respective areas are divided into blocks of 16 picture elements x 16 picture elements, for instance. At this time, even at every block, the priority is provided, and the higher priority is assigned to the block in the vicinity of the center of a screen. For instance, the priority of the block to which slashes are applied is the highest and becomes lower toward the direction shown by an arrow. When the block is actually transmitted, a threshold to decide whether the block is to be transmitted or not is determined and the threshold is changed at every area. On the area of the information especially desired to be obtained, the threshold is set to a low value to easily feed to the block in the area requiring the especially detailed information. Accordingly, the picture signal of the internal side area is easily transmitted and at the same time, a noise picture in the external area can be removed.

Description

[Detailed description of the invention] [Purpose of the invention] (Industrial application field) The present invention relates to both signal transmission systems.

(Prior art) A frame is divided into several blocks, and then information is compressed using the correlation between both signals, and the amount of information after the operation is calculated. A method of transmitting that block has been considered for some time.6 However, the amount of information is calculated sequentially starting from the upper left block within the frame, and it is difficult to obtain particularly detailed information about a specific part of the screen. Even if the information in the other part is sent, there is a possibility that the information in the other part is sent before the information in that part. Furthermore, the information you originally wanted to obtain,
There was a problem in that sufficient data was not always sent due to overflow of the sending buffer.

Additionally, frame dropping is sometimes used as a method of high-efficiency encoding, but when playing back an image on the receiving side, it is best to use a method that repeatedly outputs the frame that was actually sent. , there is a visual recognition layer in which the movement of moving images is no longer smooth, and when interpolating between frames to make the movement smooth, an interpolation device and memory for this purpose are newly installed on the receiving side. There was a need.

(5! Problems to be Solved by Ming) As described above, although compression of the image signal has been achieved to some extent in the conventional technology, deterioration in the quality of the reproduced image cannot be denied.

The present invention eliminates the drawbacks of the prior art described above.

It is an object of the present invention to provide a signal transmission method that improves visual characteristics and provides smooth reproduction of moving images.

[Structure of the invention]

(Means for Solving the Problems) This invention divides one screen into a plurality of areas, gives priority to each area, and replaces information in the area with a higher priority with information in an area with a lower priority. It is characterized in that it can be used for transmission more than

(Operation) First, decide on a specific part of the screen where you want to obtain particularly detailed information, and then divide the screen into several areas starting from that area and working your way around it. After assigning a priority, lower priorities are assigned to surrounding areas in order. Furthermore, each divided area is divided into blocks, and each block is also given a priority. In this case, if the part from which detailed information is to be obtained is, for example, a face, the priority of the blocks is determined so that the blocks are transmitted from the block near the position of the eyes, nose, or mouth of the face. do.

Next, consider frames that are sent consecutively. Divide these frames one by one into each of the above areas and set priorities, transmit more areas that correspond to specific parts where you want to obtain particularly detailed information, and reduce the number of times of transmission for surrounding areas. At that time, the number of times each area is sent is adjusted so that the overall amount of information transmitted is about the same as when frame dropping is performed, and the amount of free space in the sending buffer is checked, and a threshold is set to prevent overflow as much as possible. limit the number of blocks to be sent.

In addition, the threshold is made variable depending on the area, and blocks in areas with high priority are more easily sent by lowering the threshold. Note that when an overflow occurs, the transmission of information for one frame is stopped.

(Example) Figure 1 shows the specific configuration of the transmitting side of this system.
When the image information is input to the transmission area determination circuit tOt, only pixels included in the area to be transmitted are selected and sent to the next block division circuit 102. If the sending buffer overflows, the buffer amount detection circuit 1
A command to stop transmitting information for one frame is sent from 1G to 101. In step 102, this pixel information is divided into blocks, and then in step 103, the information in the block is compressed, and in step 104, the amount of information in the block is calculated and sent to the transmission block determination circuit 105.

Here, the information is compared with a threshold value obtained from the threshold determination circuit 111, and only those having an amount of information larger than the threshold value are quantized by the quantizer 107.

Furthermore, in the address determination circuit 106, 101, 105
A block address indicating which region and position of the block is located is determined based on the information from the block address, which is added to the quantized transmission data by the addition circuit 108 and sent to the transmission side buffer 109. In addition, the buffer amount detection circuit 110 detects the free space of the transmitting side buffer, and this information and the information sent from 101 indicating which area the block belongs to are sent to the threshold value determination circuit 111. Here, a threshold value is determined and its value is sent to 105.

FIG. 2 is a block diagram of the receiving side of this system. The information for each block that has been transmitted is stored in the receiving side buffer 20.
1, decoded by a decoder 202, and then compressed in 203, the information is decompressed and sent to the reproduction circuit 20.
Sent to 4. Here, it has a memory for one frame, and new information is written in blocks at predetermined address positions to reproduce the image. For areas or blocks that have not been transmitted, the information from one frame before is output as is as the next screen.

Next, an embodiment in which the image signal transmission system according to the present invention is applied to a video conference phone will be described. At this time, the part from which detailed information is particularly desired is a person's face, particularly around the eyes, nose, or mouth in the face. Since this face is generally placed near the center of the screen, the screen is divided into three areas as shown in Figure 3 (the number of pixels in one row of the screen is a), and then further divided. The three regions are shown independently in FIGS. 4, 5, and 6. Especially the detailed information you want to get (i.e. the eyes or nose in the face).

Generally, the area shown in FIG. 6 contains the most information, followed by the area shown in FIG. 5 and the area shown in FIG. 4. Therefore, the priority of each area is the area shown in FIG. 6 having the highest priority, followed by the area shown in FIG. 5, and then the area shown in FIG. 4.

Next, each region is divided into blocks. - As an example, assume that the image is divided into blocks of 16 pixels x 16 pixels.

At this time, a priority is set for each block, and for the above-mentioned reason, blocks near the center of the screen are assigned the highest priority. -Examples for three areas, each in 9th and 7th
8 and 9 (corresponding to FIG. 6, FIG. 5, and FIG. 4). The block with diagonal lines has the highest priority, and the priority decreases in the direction of the arrow.

Furthermore, when actually transmitting a block, a threshold value is determined to determine whether or not the block should be transmitted, and the threshold value is changed for each area.

In other words, the threshold value is set low for the area shown in Figure 6, and the threshold value is set high for the area shown in Figure 4, making it easier for blocks within the area where detailed information is required to be sent. be able to. Note that the above-mentioned threshold value can also be made variable depending on the free space of the transmitting side buffer, and it is also possible to control the number of blocks to be sent so as to prevent overflow of the transmitting side buffer as much as possible.

Now consider the case where frames are actually sent consecutively. FIG. 10 shows an example of a specific transmission method in this case. As can be seen from the figure, the area of FIG. 6 is transmitted once every two frames, the area of FIG. 5 is transmitted once every four frames, and the area of FIG. 4 is transmitted once every eight frames. In other words, one period is 8 frames, and during that period, the area in Figure 6, which is the part from which you want to obtain particularly detailed information, is examined four times, then the area in Figure 5 is examined twice, and the area in Figure 4 is examined once.
Transmit times. At this time, the number of pixels included in the area of FIG. 6 is 2 of the total number of pixels in one frame, and the number of pixels included in the area of FIG. 5 is -1 in the area of FIG. 4. 64'
When considering the entire 8 frames of 64, the number of pixels included in the area to be transmitted is as follows, which corresponds to the case where the frame is dropped one frame at a time. Moreover, the area shown in Figure 6 where detailed information is particularly required is transmitted every other frame.
The movement of the reproduced image on the receiving side is smooth in certain parts even in the same state, and there is no need for any interpolation device or extra memory on the receiving side.
The priorities of blocks to be sent in the transmission area (shaded area) in each frame in FIG. 10 are as shown in FIGS. 7 to 9, respectively.

That is, as described above, a threshold value for transmission permission is determined for each area, and the inner area has a lower threshold value, and the outer area has a higher threshold value. As a result, image signals in the inner region can be easily transmitted, and at the same time, noisy images in the outer region can be removed.

Note that in the above embodiments, any encoding method may be adopted, and the area setting is completely arbitrary. For example, in the case of a human being, multiple square areas as in the above embodiment It may be set as desired, but may be changed as appropriate depending on the shape of the image to be transmitted.

If the target object changes during signal transmission, even if A overflows and information is temporarily not sent, more of the required information will still be sent to the receiving side. Visual characteristics improve.

Moreover, the movement of the reproduced image on the receiving side is smooth in the necessary parts without the need for special equipment.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the configuration on the transmitting side of an image signal transmission system according to an embodiment of the present invention, FIG. 2 is a diagram showing the configuration on the receiving side, and FIG. 3 is a diagram showing the configuration of a frame in several areas. Figures 4, 5, and 6 are diagrams showing examples of division in the case of division into The figure shows an example of allocation when each divided area is further divided into blocks and when assigning priorities for transmission to each block. FIG. 3 is a diagram showing an example of eight frames and a transmission area within each frame. 1... Area with the lowest transmission priority, 2... Area with the second lowest transmission priority, 3... Area with the highest transmission priority, 4.5.6... Each area The block with the highest transmission priority in the block, 7...1st frame, 8...Tsugi+1st frame, 9...j+2nd frame, 10...Tsugi+3rd frame, 11 ... Tsumagi + 4th frame, 12... 4 + 5th frame, 13... Spiral + 6th frame. 14...Swamp + 7th frame. 101...Transmission area determination circuit, 102...Block division circuit, 103...Information compression circuit, 104...Information amount calculation circuit in block. 105...Transmission block determination circuit, 106...Block address determination circuit. 107... Quantizer, 108... Block address addition circuit. DESCRIPTION OF SYMBOLS 109... Transmission side buffer, 110... Buffer amount detection circuit, 111... Threshold determination circuit, 201... Receiving side buffer 202... Decoder. 203... Information decompression circuit, 204... Reproduction circuit. Agent Patent Attorney Nori Ken Yudo Takehana Kikuo No. 1 Figure 2ρl: 孡戟城Yahooa Figure 3 Figure 4 Figure 6 Figure 6 Figure 9

Claims (2)

[Claims] (1) A screen characterized by dividing the screen into a plurality of areas, giving priority to each area, and transmitting more information in areas with higher priority than information in areas with lower priority. Signal transmission method. (2) The image according to claim 1, characterized in that the divided area is further divided into blocks, each block is given a priority order, and the block with the higher order is transmitted first. Signal transmission method.