JPH02127872A - Picture transmitting equipment - Google Patents

Abstract

PURPOSE:To prevent the deterioration in the picture quality by allowing a transmitter to split the screen into plural areas and to encode a signal for each area and sending a block being the result of adding area location information to the coded signal and allowing a receiver to decode an original picture signal while deciding the area location of a decoded signal on the screen based on the area location information. CONSTITUTION:A picture transmitting equipment which applies band compression coding to a picture at the sender side and sends a compressed signal to a receiver side via a communication network through which the information is sent intermittently in the unit of blocks, splits one screen into plural areas, applies compression coding to a signal for each area and sends a block being the result of adding area location information to the compressed signal at each to the receiver side. Moreover, while the area location of the decoded signal on the screen is decided based on the area location information added to a received block, the receiver decodes the compressed signal of the received block to decode the signal into the original picture. Thus, while the decoded location of the received picture signal on the screen is guaranteed, the picture signal is decoded and the deterioration of the picture quality is prevented.

Description

[Detailed Description of the Invention] [Summary] An example of a transmitting device performs band compression encoding (high-efficiency encoding) on an image signal to transmit information through a communication network such as a packet communication network that transmits information intermittently in blocks. Regarding the image transmission device that transmits to the receiving device side.

The purpose of this invention is to prevent deterioration of image quality by making it possible to restore an image signal while guaranteeing the restoration position of the received image signal on the screen even when blocks are discarded or their order is changed.

The transmitting device is configured to divide one screen into a plurality of regions, encode each region, and transmit a block obtained by adding the region position information to the encoded signal of each region to the receiving device side. The device determines the region position t added to the received block.
The present invention is characterized in that it is configured to decode the encoded signal of the received block and restore the original image signal while determining the area position of the decoded signal on the screen based on the TT information.

[Industrial application field]

The present invention relates to an image transmission device that performs band compression encoding of an image signal on the transmitting device side and transmitting the image signal to the receiving device side via a packet communication network or the like.

Such image transmission devices are used in various fields such as video conference calls, centralized image monitoring in offices and plants, and broadcasting typified by TV to C. It is necessary that even if a replacement occurs, it will not be difficult to restore the image in the example receiving device.

[Conventional technology]

Conventional image communication systems have been developed on the premise that the transmission path used is a fixed band, constant transmission delay time, and random error occurrence. In such a communication system, even when there is little movement in the image to be transmitted and there is no need to transmit data, dummy data is transmitted so as to use up the bandwidth of the transmission path, resulting in poor transmission efficiency. In addition, if the amount of data to be sent exceeds the bandwidth due to rapid image movement, the amount of data to be sent is reduced by thinning the data to be sent. Quality deteriorates.

Therefore, in recent years, there has been active research and development using packet communication, which has been developed in computer communication, to increase the speed and capacity of single image communication by taking advantage of the feature of packet communication that allows only necessary data to be transmitted. According to this packet communication network, only the data that actually needs to be transmitted can be transmitted as necessary and sufficient.

[Problem to be solved by the invention]

In a packet communication network, packets may be discarded within the network or the order in which the packets arrive at a receiving terminal may be changed. Therefore, if a part of the image signal that reaches the receiving terminal is missing, or if a packet arrives in the reverse order after a period of time that guarantees that the order is swapped between terminals, the receiving side will receive the image signal sequentially. Therefore, it becomes impossible to guarantee the time-sequentiality of the image signal. As a result.

The image data used for encoding on the encoder side is decoded; +
Since the data is no longer present on the decoder side, the decoder side uses incorrect data to restore the image, making it impossible to restore the image correctly.

Furthermore, even if there is no need to send an image signal because there is no movement in the image on the sending side, it is necessary to send packets that have no meaning as data in order to guarantee the time-sequentiality of the image signal on the receiving side. There are also issues like this.

Therefore, an object of the present invention is to restore the image signal while guaranteeing the restoration position of the received image signal on the screen even if blocks (packets) are discarded or their order is changed. The goal is to prevent the deterioration of

[Means to solve the problem]

FIG. 1 is a diagram explaining the principle of the present invention.

An image transmission device according to the present invention is an image transmission device that performs band compression encoding on an image on the transmitting device side and transmits a compressed signal to the receiving device side via a communication network that intermittently transmits information in m blocks. , the transmitting device is configured to divide one screen into a plurality of regions, compress and encode each region, and transmit a block in which region position information is added to the compressed signal of each region to the receiving device side. The device is configured to determine the area position of the decoded signal on the screen based on the area position information added to the reception block, and decode the compressed signal of the reception block to restore the original image signal. be.

Further, in the image transmission device according to the present invention, as an lt+ form, the transmitting device further includes a detection means for detecting the amount of change in one image, and prevents the image compressed signal from being transmitted to the receiving device side for an area where the change meter is small. It is composed of

Furthermore, the image transmission device according to the present invention has other shapes! As such, the transmitting device includes the image signal of the pixel at the beginning of the block as a reference signal in the transmitted image data of each area without compression encoding, and the receiving device uses this reference signal as a reference value for image restoration. It is configured to perform image restoration while being used as a computer.

[Effect]

The image to be transmitted is divided into multiple regions.

Band compression encoding is performed for each region. A transmission block is created corresponding to each area and transmitted to the receiving side.

This transmission block includes a compressed signal of the area and area position information for determining the area position.

Therefore, on the receiving side, it is possible to determine at which position on the restored screen the compressed signal of the received block is located based on this area position information. As a result, even if blocks are discarded or the like and the time-sequential nature of the received signal is impaired, the image can be restored for each region without being affected by blur.

In addition, in the aspect of the present invention, the transmitting side detects for each area whether there is a command etc. in the image to be transmitted, and
], etc., the block is not transmitted, and upon reception, in this case, the past restored image is used to restore the current image.

This eliminates the need to transmit unnecessary information and improves transmission efficiency.

Furthermore, in the aspect of the present invention, a non-compression encoded image @ signal is included as a reference signal as the image data of the pixel at the beginning of each area, and this reference signal is used when restoring the image of each area in the reception example. The image is used as it is as a restored image and the subsequent pixels are restored. As a result, even when using compression encoding in which image restoration is impossible if the previous value is lost, such as in previous value prediction, it is possible to prevent image restoration of the current block from being impossible due to the loss of the restored image of the previous block. It can be prevented.

〔Example〕

The present invention will be described in detail below with reference to one drawing. Second
The figure is a block diagram showing a transmitting device of an image transmitting apparatus as an embodiment of the present invention, and FIG. 3 is a block diagram showing a receiving device thereof.

In FIG. 2, the transmitter includes an A/D converter 1 a phase detector 2 . Bank it, II control section 3. Swift parts 4, 8 and 10
．． Frame Panzer Memory Control Unit 5. Frame expansion memory sections 6 and 7. Encoding unit 9. Packet m stand section 11.
Transmission buffer 12. It is configured to include an error calculation section 13 and the like.

The Δ/D converter 1 converts the manually input analog image signal into a digital image signal, and the phase detector 2 detects the horizontal/facet signal from the image signal from the A/I) converter 1 and detects the horizontal /! I! It generates a direct synchronization timing signal and sends the timing signal to the bank control section 3 and frame buffer memory control section 5.

The bank control unit 3 uses the vertical synchronization timing signal from the phase detection unit 2 as a trigger to switch the switch unit 4 for each frame, and transfers the input image signals to two frame buffer memory units 6 and 7 alternately for each frame. It works as if it were input. The frame buffer memory units 6 and 7 are for storing digitized image signals in frame units.

Based on the timing signal output from the phase detection section 2, the frame buffer memory control section 5 sends a write address and a write timing signal to the memory section selected as the current frame among the frame buffer memory sections 6 and 7. and send read address and read timing signals 44. to both frame buffer memory units 6 and 7 on two sides. Ori.

I can do it. Further, a selection signal for selecting the current frame side memory section from frame buffer memory sections 6 and 7 is given to the switch section 8, and a compressed signal from the encoding section 9 and a selection signal from the switch section 8 are sent to the switch section IO. A selection signal is given to select either the direct output from the

Further, the frame buffer memory control unit 5 provides the packet assembling unit 11 with an area identifier for identifying the area being read from the frame buffer memory units 6 and 7, and timing signals for starting and ending the area. Here, the regions are regions E1 to En when one screen is divided into a plurality of regions, as shown in FIG.

The encoding unit 9 is a circuit that performs predictive encoding (band compression encoding) on the image signal of the current frame manually inputted via the switch unit 8, and includes a subtracter 91. Quantizer 92. Additional base 9
3. The compressed signal is input to one input terminal of the switch section 10. The output image signal from the switch section 8 is directly inputted to the other input terminal of the switch section 10.

The error calculation unit 13 reads out the image signal of the current frame and the image signal of the previous frame from the frame buffer memory units 6 and 7, calculates the least square error between both signals, compares this with a predetermined threshold value, and calculates the least square error between the two signals. Depending on the result, a transmission/discard command signal is sent to the packet assembler 11.

The switch section 10 selects each area E1 to E1 from the switch section 3 according to a selection signal from the frame buffer memory control section 5.
The switching timing is controlled so as to select either the image signal of the first pixels P1 to Pn of En or the compressed signal of the other pixel portion (remaining pixels in the area) from the encoding unit 9.

The packet assembling unit 11 is a circuit that assembles a packet by adding a packet header to the image data signal from the switch unit 10 based on the timing signal from the frame buffer memory control unit 5. The area identifier is inserted into. Also, the error calculation unit 13
If the command signal from is a transmission command, the packet is output to the transmission buffer 12, and if it is a command to discard F, the packet is discarded.

In FIG. 3, the receiving device includes a receiving buffer 21, a packet disassembling unit 22. Frame buffer memory control unit 23.
Gate section 24. Decoding unit 25. Frame buffer memory section 26. It is configured to include a D/A converter 27 and the like.

The packet decomposition unit 22 decomposes the received packet into a compressed signal and a header storage area identifier, outputs the compressed signal 3 to the gate unit 24 and the decoding unit 25, and also outputs the area identifier to the frame buffer memory control unit 23. Output. The decoding unit 25 includes a subtracter 251, a predictor 252, and the like, and has a function as a restorer that outputs a restored image signal.

The restored image signal is output to the frame buffer memory section 26. The frame buffer memory section 26 has been restored.
It records frame image signals.

Based on the received area identifier, the frame buffer memory control unit 23 outputs a write address and a write timing signal, and a read address and a read timing signal to the frame buffer memory unit 26 corresponding to the area, and also outputs a gate opening/closing signal to the gate unit 24. Output a signal. D
The /A conversion unit 27 converts the data obtained from the frame buffer memory unit 26 into an analog image signal.

The operation of the embodiment device will be explained below. First, the operation of the transmitting device shown in FIG. 2 will be explained. The input image signal is A/D
Each frame is switched and stored in the frame buffer memory section 6 or 7 via the conversion section 1 and the switch section 4. Switching control of the switch section 4 is performed at timing for each frame based on a switching signal from the bank control section 3.

Thereby, the frame buffer memory sections 6 and 7.

The image signal of the current frame is alternately stored in one and the image signal of the previous frame is stored in the other.

The write address to the frame buffer memory section 6 or 7 is specified by the frame buffer memory control section 5.

Of the frame buffer memory units 6 and 7, the memory unit on the current frame side is selected by the switch unit 8 in accordance with a command from the frame buffer memory control unit 5, and the current frame image signal is sent to the encoding unit 9. encoded. This encoding of the image signal is performed for each of a plurality of regions E1 to En as shown in FIG.

The compressed image signal encoded by the encoding section 9 is sent to the Swissochi section 1.
0 to the packet assembling section 11 manually. At this time, the switch section 10 is connected to each area E.

At the input timing of the image signals of pixels P and -Pn at the top position of ~En, the direct image signal from the switch section 8 is selected, and at other times, the compressed signal from the encoding section 9 is selected. As a result, the image data input to the package 7) assembling unit 11 is for each region E1 to E1? , the first pixel P of n,
~Pn, unencoded pixel signals are input as they are, and encoded compressed signals are input to the remaining pixels in the remaining area. The image signals of the first pixels P1 to Pn are used as reference signals during decoding on the receiving side.

The packet assembling unit 11 creates packets for each area using the input image data. At this time, in the header part of the packet, 3 is added to the image data area E of the packet.
Stores an area identifier indicating ~En.

The error calculation unit 13 calculates the amount of change (for example, amount of movement) in each image area.
Calculate. This amount of change can be determined by determining the least squares error between the image signal of the current frame and the image signal of the previous frame for each region, and whether or not it exceeds a predetermined threshold.

If the amount of change is small, the image of the previous frame can be used on the receiving side without sending the image data of that area to the receiving side, so in that case, a packet discard command signal is sent to the packet assembling unit 11. On the other hand, if the amount of change is large, it is sent to the transmission ih multiple signal packet assembly section 11.

The packet assembling unit 11 determines whether to transmit or discard the created packet in response to the transmission/discard command signal from the error calculation unit 13, and in the case of transmission, sends the packet to the receiving device side via the transmission buffer 12. send.

In the receiving device shown in FIG. 3, a received packet is passed through a reception buffer 21 to a packet decomposition unit 22 and decomposed into one image data and an area identifier.One image data is sent to a decoding unit 25, and the area identifier is It is manually input to the frame buffer memory skewer control section 23.

The decoding unit 25 decodes the manually input compressed image signal to restore the original image signal, and stores this in the frame buffer memory unit 26. At this time, the first pixel P of each area ~Pn
Only then, the gate section 24 is controlled to open and close so that the received image signal is manually input to the frame panzer memory section 26 as it is. This image signal is also feed-hacked to the decoding unit 25 as a restored image signal, and is used to generate a predicted signal.

The frame buffer memory control unit 23 uses the area identifier of the received packet to determine which area on the restored screen the image data of the received packet belongs to.
Therefore, it is possible to control the restored image signal of the decoding section 25 to be corrupted to the address of the area position of the frame panzer memory section 26.

As a result, even if the received image data is not guaranteed to be time-sequential due to packet discard, etc. (i.e., image data is missing for the area), the received image data can be transferred to the correct area position on the screen. No. 19 can be made while corresponding to the above.

For the missing 'i'/l region portion, it is possible to use a method such as using the restored image of the previous frame as is.

Also, when converting the image data of each area into 19 elements.

The predicted value can be calculated using the uncoded first pixel (■) of the area as a reference signal, and subsequent pixels can be decoded. Restoring data will not be difficult.

Various modifications are possible in implementing the invention. For example, in the embodiment, a predictive encoding method is used as the image signal encoding method, but of course the present invention is not limited to this, and various other band compression encoding methods can be used. Further, although the packet communication method is used as the image signal transmission method, the present invention is not limited to this, and other communication methods that transmit transmission data intermittently (burst-like) in units of blocks may be used. Furthermore, the method of dividing the image area is not limited to that of the embodiment.

[Brief explanation of the drawing]

FIG. 1 is a diagram explaining the principle of the present invention. FIG. 2 is a block diagram showing the transmitting device side of an image transmitting device as an embodiment of the present invention. FIG. 3 is a block diagram showing the receiving device side of the image transmission device as an embodiment of the present invention. FIG. 4 is a diagram illustrating division of an image area by the embodiment apparatus. In fig. ] - A/D conversion unit 2 - Phase detection unit 3 - Bank control unit 4.8.10 - Switch unit 5.23 - Frame buffer memory 1bll? f
16.7.26 - Frame buffer memory section 9 - Encoding section 11 - Packet assembly section 12 - Transmission bath sofa 13 - Error calculation section 21 - Receiving bath sofa Packet disassembly section Gate section Decoding section D/A conversion section (, 5. Koji gishi 14 rules] 4th day and month 4 L; Shell 11 Figure 3 a J I Elephant's area ratio I series Figure 4

Claims (1)

[Scope of Claims] 1. An image transmission device that performs band compression encoding on an image on the transmitting device side and transmits the compressed signal to the receiving device side via a communication path that transmits information intermittently in blocks, comprising: The device is configured to divide one screen into a plurality of regions, encode each region, and transmit a block in which region position information is added to the compressed signal of each region to the receiving device side, and the receiving device , characterized in that it is configured to determine the area position of the decoded signal on the screen based on the area position information added to the reception block, and to decode the compressed signal of the reception block to restore the original image signal. image transmission device. 2. The image transmitting device according to claim 1, wherein the transmitting device includes a detection means for detecting the amount of change in the image, and is configured not to transmit the encoded image signal to the receiving device for areas where the amount of change is small. 3. On the transmitting device side, the image signal of the pixel at the beginning of the block is included as a reference signal without being compressed and encoded in the transmitted image data of each area, and on the receiving device side, this reference signal is used as a reference value for image restoration. 3. The image transmission device according to claim 1, wherein the image transmission device is configured to perform image restoration while being used.