JPH10224746A - Image transmission system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize high quality image transmission through quick processing even on the occurrence of an error in the case that an image frame of a transmission object is divided into a plurality of block data and the block data are sequentially sent from a transmitter side device to a receiver side device. SOLUTION: In the transmitter side device 1, a transmission means is configured by an image transmission control means 13 and a transmitter side communication control means 14, and the transmission means 15 sends sequentially block data as to the same part in an image frame being a transmission object to a transmission line 3 for a prescribed number of times, twice or over. On the other hand, in the receiver side device 2, a reception means is configured with a receiver side communication means 21 and a receiver side communication control means 22, the reception means receives sequentially the block data sent from the transmitter side device 1 via the transmission line 3 and a re- configuration means 23 selects normal block data among a plurality of block data received as to the same part in an image frame and re-configures the image frame.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image transmission system which divides an image frame to be transmitted into a plurality of block data and sequentially transmits the block data from a transmitting apparatus to a receiving apparatus. The risk of errors is reduced by transmitting the block data for the same part a plurality of times from the transmitting device, and the receiving device reconstructs the image frame by selecting normal block data from the plurality of received block data. To an image transmission system.

[0002]

2. Description of the Related Art In an image transmission system for transmitting an image,
For example, an image frame to be transmitted is divided into a plurality of block data, and these block data are sequentially transmitted from a transmitting apparatus to a receiving apparatus via a transmission path. In such a system, when an error due to a transmission failure or the like occurs in the block data transmitted from the transmitting apparatus, the receiving apparatus normally reconstructs an image portion corresponding to the erroneous block data. Can not do. In particular, when a low-quality transmission path such as a wireless transmission path is used, a large number of block data errors may occur due to a transmission failure, and in such a case, many errors in the original image frame may occur. Is not properly reconstructed.

[0003] In the above-described image transmission system, an image frame to be transmitted is generally transmitted to an H.264 image by a transmitting apparatus. H.263, MPEG1 and other methods are used to reduce the amount of data required for transmission.
In these encoding methods, for example, as shown in FIG.
The image frame 80 is divided into a plurality of block data 81a, 81b, 81c,... Such as MB (macroblock) data and MCU (minimum coding unit) data, and the encoding process is performed. A block data string 85 composed of several of these block data is represented by G
It is called an OB (group of blocks) or a slice, and is generally a unit of encoding when performing encoding processing using correlation between block data on block data.

For example, a block data sequence 8 shown in FIG.
5 is composed of a plurality of block data arranged in a band in the horizontal direction in the image frame 80. As a method of encoding these block data by correlation between the block data, for example, the block data 81b located at the second position from the left in the block data sequence 85 is correlated with the block data 81a located at the leftmost position. Similarly, the block data 81c located third from the left is replaced with the block data 81b located second from the left.
In this case, each block data is coded based on a correlation with block data adjacent to the block data, such as coding based on a correlation with the block data.

On the other hand, in the decoding process, since the block data located on the leftmost side in the block data string 85 has not been subjected to the encoding process using the correlation between the block data, A series of block data encoded as described above is sequentially decoded based on the located block data. That is, first, the block data 8 located at the leftmost position in the block data sequence 85
The block data 81b located second from the left is decoded by the correlation with 1a, and the third block data 81c from the left is decoded by the correlation with the decoded block data 81b. Then, each block data is sequentially decoded by correlation with the decoded block data adjacent to the block data.

For this reason, when an error occurs in certain block data in a block data sequence due to a transmission failure or the like when transmitting block data from a transmitting apparatus to a receiving apparatus, for example, as shown in FIG. In addition, not only the block data in which an error has occurred, but also the block data on the right side and the block data on the right side that are decoded by the correlation with the block data cannot be similarly decoded. As a result, However, the block data located on the right side of the block data in which the error has occurred cannot be decoded normally. Therefore, the image portion corresponding to the block data that could not be decoded normally cannot be properly reconstructed.

With respect to the block data error as described above, the error occurring in the block data is detected by the receiving side device, and the error detected by the retransmission system (ARQ), the error correction system (FEC) or the like is detected. It has been done to deal with. For example, in the retransmission method, when the block data transmitted from the transmitting apparatus is normally received by the receiving apparatus, a response signal notifying that the block data has been normally received is transmitted from the receiving apparatus. Sent to As a result, the transmitting apparatus regards the block data for which the response signal has not been received as being not normally received by the receiving apparatus, and transmits this block data to the receiving apparatus again, thereby transmitting the block data. Perform retransmission processing. In the error correction method, for example, an error correction code for correcting an error is added to each block data, and the receiving side device corrects an error generated in the block data using the error correction code.

[0008]

However, in the above-mentioned retransmission method, for example, every time block data of the same portion in an image frame is transmitted once from the transmitting apparatus, the transmitting apparatus responds from the receiving apparatus. Since the presence or absence of a signal is checked and retransmission is performed if necessary, there is a problem that these processing functions become complicated. If the same block data has to be transmitted many times due to bad transmission path conditions, etc., the above-described response signal confirmation processing must be performed the same number of times. This causes a problem that image transmission is delayed.

Further, for example, when a block data sequence in which a plurality of block data are combined is used as a transmission unit, an error occurs at the same timing when transmitting the block data sequence depending on the system situation. Therefore, there is a problem that even if the retransmission processing is performed as described above, errors are always concentrated on block data transmitted in the same transmission order.

In the above-described error correction system, for example, each block data is error-correction-coded and transmitted from the transmitting device, and the error-correction-coded block data is received by the receiving device and subjected to error correction decoding. Therefore, there is a problem that the processing function becomes complicated as in the case of the retransmission method described above. In general, an error correction code has an error correction capability, which is a limit at which an error can be corrected. When an error exceeding the error correction capability occurs in block data, the error of the block data is corrected. There was a problem that the error could not be corrected.

The present invention has been made to solve such a conventional problem, and the same block data in an image frame to be transmitted is transmitted from a transmitting apparatus to a receiving apparatus a plurality of times, and an error occurs. It is an object of the present invention to provide an image transmission system capable of realizing high-quality image transmission by quick processing by selecting and reproducing normal data from these block data even in the case of performing . More specifically, it is possible to reduce a delay in image transmission caused by a response signal confirmation process performed by the transmitting device performed by the above-described retransmission method. As long as no errors occur in all of the same block data, even if an error that exceeds the error correction capability of the error correction code occurs, normal block data is selected and the image frame is reconstructed. It is an object of the present invention to provide an image transmission system capable of performing the above.

Further, the present invention is applicable to a case where an error occurs at the same timing when transmitting a block data sequence in which a plurality of block data are combined as a transmission unit. It is an object of the present invention to provide an image transmission system capable of preventing errors from being concentrated on block data. Further, according to the present invention, a plurality of block data in an image frame to be transmitted are grouped into a block data sequence, and the encoding direction of the same block data sequence is inverted between one block data sequence and the other block data sequence. Then, the block data is encoded using the correlation between the block data and transmitted from the transmission side device, and even if an error occurs, a normal one is selected from these decoded block data. It is an object of the present invention to provide an image transmission system capable of realizing high-quality image transmission by rapid processing by reproducing.

[0013]

In order to achieve the above object, in an image transmission system according to the present invention, an image frame divided into a plurality of block data is transmitted from a transmitting device to a receiving device as follows. I do. In the transmitting device,
The transmitting means sequentially transmits the block data of the same part in the image frame to be transmitted two or more times in advance. On the other hand, in the receiving device, the receiving means sequentially receives the block data transmitted from the transmitting device, and the reconstructing means selects normal block data from a plurality of block data received for the same portion in the image frame. Reconstruct the image frame.

Therefore, if the receiving apparatus can normally receive the block data transmitted a plurality of times from the transmitting apparatus for the same portion in the image frame one or more times, the receiving apparatus uses the normally received block data. Thus, the image frame transmitted from the transmitting apparatus can be reconstructed. That is, as long as no error occurs in all of the block data transmitted a plurality of times for the same portion in the image frame, normal block data is selected from the received plurality of block data to reconstruct the original image frame. As a result, high-quality image transmission can be realized by rapid processing.

[0015] In the image transmission system according to the present invention, the transmitting means provided in the transmitting apparatus transmits a block data sequence in which a plurality of block data are combined as a transmission unit, and transmits the same block data sequence in the image frame. Is transmitted with the arrangement order of the block data included in the other block data sequence reversed with respect to the one block data sequence. Therefore, when sequentially transmitting a plurality of block data included in the block data sequence, even if there is a situation where an error is likely to occur at the same timing, etc., one block data sequence and the other block data Since the transmission is performed with the arrangement order of the block data being inverted between the columns, it is possible to prevent the occurrence of errors from being concentrated on the same block data.

Further, in the image transmission system according to the present invention, the transmitting apparatus further collects a plurality of block data into a block data sequence, and converts the block data between the block data in the encoding direction along the block data sequence. Encoding means for encoding by using the correlation of, and for the same block data string in the image frame, one of the block data strings is encoded by the encoding means and the other block data string is inverted in encoding direction. And an inversion encoding means for encoding by the encoding means, and transmits the block data encoded by the transmission means. The receiving apparatus further includes decoding means for decoding the coded block data received by the receiving means in accordance with the coding direction, wherein the reconstructing means performs a normal operation on the decoded block data from the decoded block data. Select block data.

Therefore, when the block data is encoded using the correlation between the block data in the encoding direction along the block data sequence and transmitted from the transmitting side device a plurality of times, the same block in the image frame to be transmitted is transmitted. With respect to the data sequence, the encoding direction is reversed between one block data sequence and the other block data sequence to perform encoding, whereby the decoding direction of these block data sequences can be reversed. As a result, the receiving apparatus can reduce the rate of occurrence of a situation in which all of a plurality of block data received for the same part in an image frame are not correctly decoded, and high quality can be achieved by rapid processing. Image transmission can be realized.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment according to the present invention will be described with reference to the drawings. FIG. 1 shows an example of an image transmission system according to the present invention.
The apparatus includes a transmitting device 1 that transmits an image, a receiving device 2 that receives an image, and a transmission path 3 that connects these two devices. An image input unit 11 for inputting an image, an image encoding unit 12 for encoding an image,
The transmission apparatus 1 includes an image transmission control unit 13 for controlling a transmission process, a transmission communication control unit 14 for controlling an image communication process, and a transmission communication unit 15 for transmitting an image.

The image input means 11 receives an NTSC composite signal, a Y / C signal, and a PAL signal via an image storage device such as a VTR or a camera using a solid-state image sensor such as a CCD.
It is means for inputting a video signal such as a signal. An arbitrary image such as a still image or a moving image may be input as an image input by the image input unit 11, but in this example, moving image data composed of a plurality of continuous image frames is input. The image coding means 12 is means for coding an image frame. Examples of the coding method include a method of coding an image frame using intra-frame correlation, such as a JPEG method, and a method of encoding an image frame. H.261 system and H.264. For example, a method of encoding an image frame using the inter-frame correlation, such as the H.263 method, the MPEG1 method, or the MPEG2 method, is used.

In this example, the image encoding means 12 converts the image frame 31 into a plurality of MBs as shown in FIG.
The data 33 is divided into a plurality of MB data of one row arranged in the horizontal direction in the image frame. The GOB 32 is used as a unit of encoding, and each MB data is divided between the MB data in the encoding direction along the GOB. Is coded using the correlation in.
At this time, in this example, the MB located on the leftmost side in the GOB is
The data is not coded, but each MB data is coded by using the correlation between the MB data and the MB data adjacent to the left side of the MB data, and this is set as the GOB coding direction.

As shown in FIG. 3, the image transmission control means 13 comprises a transmission control section 131 and a transmission-side temporary storage section 132. The transmission control section 131 converts each coded image frame into each MB. Retrieve the data and read each of these MBs
Image ID which is an identifier for specifying an image frame in data
, A group ID (GOB ID) which is an identifier for specifying a GOB in an image frame, and a block ID which is an identifier for specifying an arrangement order of MB data in the GOB
(MB ID) and outputs the MB data to which these IDs have been added.
This is a means for storing the information.

Here, as an example of the above-mentioned addition of IDs, for example, when numbers such as 1, 2, 3,... Are used as each ID, as shown in FIG. For example, an image ID for specifying the image frame 31
34 (image ID = 1), a group ID 35 for specifying the GOB 32 (group ID = t), and a block ID 36 for specifying the arrangement order of the MB data 33 in the GOB 32
(Block ID = 1). In this example, the group ID and the block ID are used to determine the MB.
The position of the data in the image frame has been identified.
It is sufficient that the position of each MB data in the image frame is specified. For example, the position of each MB data in the image frame is specified by adding a serial number as an ID to each MB data constituting one image frame. May be.

The transmission-side temporary storage section 132 is a means for storing MB data to which an ID has been added as described above. In addition, the transmission control unit 131, together with the means described above,
There is provided means for reading out and outputting the MB data stored in the transmitting-side temporary storage section 132. With the above configuration, the image transmission control means 13 adds each ID described above to each MB data constituting the image frame, outputs them, and outputs the same image frame stored in the transmission side temporary storage unit 132. By reading out the MB data for and outputting these, the MB data for the same part in the image frame can be output an arbitrary number of times.
When the processing for one image frame by the image transmission control means 13 is completed and the processing for the next image frame is started, the MB data stored in the transmission-side temporary storage unit 132 is deleted once. Is also good.

The transmission-side communication control means 14 is provided with each of the I
An error detection code is added to the MB data to which D has been added, and these MB data are sequentially transmitted by the transmission side communication means 15 using, for example, a frame format of an HDLC (High Level Data Link Control) procedure. Also,
The transmitting side communication means 15 is means for transmitting and outputting the MB data to the transmission path 3, and is composed of a modulator for modulating the data. Here, the image transmission control means 13 transmits the MB data for the same part in the same image frame to the transmission path 3 via the transmission-side communication control means 14 to the transmission path 3 by the transmission-side communication means 15. The transmission means is constituted by transmitting the number of times. With the above configuration, the transmission-side apparatus 1 divides each image frame constituting the input moving image into a plurality of MB data, and sets the MB data for the same part in the same image frame in the transmission path 3 in advance. It is transmitted two or more times.

The receiving device 2 includes a receiving communication device 21 for receiving an image, a receiving communication control device 22 for controlling an image communication process, and an image receiving device for controlling a receiving process in the receiving device 2. Control means 23, image decoding means 24 for decoding an image, and image output means 2 for outputting an image
5 are provided. The receiving-side communication unit 21 is a unit that receives MB data via the transmission path 3 and includes a demodulator that demodulates data corresponding to the transmitting-side device 1. The receiving-side communication control means 22 controls the receiving process by the receiving-side communication means 21 and receives the received MB.
This is a means for detecting whether an error has occurred in the MB data by the error detection code added to the data. here,
The receiving-side communication control means 22 receives the MB data via the transmission path 3 by the receiving-side communication means 21 to constitute a receiving means.

As shown in FIG. 4, the image reception control unit 23 includes an image reception control unit 231 and a reception-side temporary storage unit 232.
, And an MB error detection result storage unit 233 and an alternative MB storage unit 234. The image reception control unit 231 reads the above-mentioned IDs from the input MB data, stores the normal MB data in the reception-side temporary storage unit 232, and stores the group ID and block ID of the normal MB data in the MB. This is a means for notifying the error detection result storage unit 233. Even if normal MB data is input to the image reception control unit 231, if the same normal MB data is already stored in the receiving-side temporary storage unit 232, the normal MB data is not necessarily stored. The same MB data as the stored data is again stored in the receiving-side temporary storage unit 232.
There is no need to memorize it.

The above processing by the image reception control unit 231 is performed for each MB data having the same image ID. Therefore, when the image ID of the MB data changes, as described later, the reception side temporary The storage contents of the storage unit 232 and the MB error detection result storage unit 233 are initialized once. The receiving-side temporary storage unit 232 includes a frame memory and the like.
This is means for storing and holding the B data at a position in the frame corresponding to the group ID and the block ID. Also, when the image ID of the MB data changes, the receiving-side temporary storage unit 2
The MB data stored in 32 is once erased, and subsequently, a process of storing the MB data for the next image ID is performed.

The MB error detection result storage unit 2
A unit 33 stores a group ID and a block ID for normal MB data among MB data having the same image ID. As this storage method, in this example,
An identification value is provided corresponding to each image portion specified by a combination of the group ID and the block ID, and an identification value “1” is assigned to an image portion to which normal MB data has been input. An identification value “0” is assigned to an image part that has not been input. Also, MB
When the image ID of the data changes, the identification values stored in the MB error detection result storage unit 233 are all once "
Then, the identification value of the image portion corresponding to the normal MB data for the next image ID is sequentially set to “0”.
From “1” to “1”.

The alternative MB storage unit 234 is a means for storing in advance alternative MB data which can be normally decoded by the image decoding means 24 described later. The MB data is allocated to the image part for which no MB data was obtained. In addition, the image reception control unit 231 transmits the input MB
When the image ID of the data changes, the receiving-side temporary storage unit 23
2. The MB data stored and held as a frame is read out, and the above-mentioned alternative MB data is assigned to an image portion in which normal MB data cannot be obtained in this frame, and the MB data for one frame is output. Means are provided. Note that a normal M
The image portion for which the B data has not been obtained can be specified with reference to the MB error detection result storage unit 233 described above.

With the above configuration, the image reception control means 23
The reconstructing means is configured by selecting normal MB data from a plurality of MB data received for the same part in the same image frame and reconstructing the image frame. The image decoding unit 24 is a unit that decodes an encoded image frame according to an encoding method. The image output means 25 is composed of, for example, a display screen,
This is a means for displaying and outputting a moving image by sequentially displaying a plurality of continuous image frames on this screen. With the above configuration, the reception-side apparatus 2 transmits the MB data to the transmission path 3
Via the received MB data and the normal MB
The data is selected to reconstruct an image frame, and the reconstructed image frame is displayed and output as a moving image.

Next, an image transmission process performed by the image transmission system having the above configuration will be described with reference to an example of the process shown in FIG. In this example, an example in which MB data of the same part in an image frame to be transmitted is transmitted twice will be described. As shown in FIG. 5A, the transmitting apparatus 1 inputs a moving image to be transmitted (Step S).
1) The respective image frames constituting the input moving image are sequentially encoded (step S2). Then, as for the encoded image frame, first, a plurality of MB data constituting this image frame is transmitted to the transmission path 3 as the first transmission (step S3), and then, the same image frame is transmitted. The same MB data is similarly transmitted to the transmission path 3 as the second transmission (step S4). In this way, each image frame to be transmitted is transmitted twice from the transmitting device 1.

On the other hand, in the receiving device 2, as shown in FIG. 5B, for each image frame transmitted from the transmitting device 1, first, the MB data transmitted for the first time is transmitted via the transmission path 3. (Step S11), and the received M
The normal B data is stored at the corresponding position in the frame (step S12). Also, the second transmission of the MB data for the same image frame is received via the transmission path 3 (step S13), and the first transmission was not normally performed but the second transmission was normally performed. The MB data is stored at the corresponding position in the frame together with the normal MB data stored for the first time (step S14). Then, the image frame thus reconstructed is decoded (step S15) and displayed on the screen as a moving image (step S16).

As described above, in the receiving side device 2, 1
Normal MB data is selected from the image frame received the second time or the image frame received the second time, one image frame is reconstructed, and the reconstructed image frame is decoded. That is, M in which an error occurred in the first reception
If the B data and the erroneous MB data in the second reception are not at the same position in the image frame, the receiving side device 2
Can select one MB of normally received data to obtain data of one image frame as normal received data, and decode this to obtain one normal image. Can be played.

For example, FIG. 6A shows an image frame 41 decoded from the first received MB data including the MB data having a reception error, and FIG.
From the MB data received the second time, the M with the reception error
The image frame 42 decoded including the B data is shown. Here, in these image frames 41 and 42, the position of the erroneous MB data is indicated by a black rectangle, and the image that cannot be decoded normally due to the erroneous MB data is shown. Portions are indicated by diagonal lines.

In this embodiment, before performing the decoding process of the MB data, the normally received MB data from the first or second received MB data, that is, a black square in the frames 41 and 42 is used. MB other than the indicated part
By selecting data and combining them, the received data is reconstructed as one image frame. When this frame is decoded, since the error occurrence positions of the MB data are different between the frames 41 and 42, the image frame 43 without any error is reproduced as shown in FIG. You.

Here, the MB at the same position in the image frame
If the data is not normally received in both the first reception and the second reception, the MB data and the MB data are not received.
Data cannot be normally reproduced for an image portion that cannot be decoded normally due to the data. However, for a position in a frame where MB data has been normally received at least in one of the first reception and the second reception, normal MB data can be selected and assigned. For this reason, according to the present embodiment, as shown in FIGS. 6A and 6B, for example, as compared with the case where an image is reproduced only from MB data obtained by one reception, a larger number of errors are generated. An image can be reproduced with a reduced number of portions, whereby high-quality image transmission can be realized by rapid processing.

Here, in the above embodiment, the image frame to be transmitted is encoded by the transmitting side apparatus 1 and
In the above, the image frame was decoded, but these encoding and decoding processes need not always be performed. Further, in the above-described embodiment, an example in which the MB data is transmitted from the transmitting device 1 to the receiving device 2 as a transmission unit has been described.
A GOB in which a plurality of B data are combined may be transmitted as a transmission unit. In such a case, for example, an error may always occur in the same MB data even if the same GOB is transmitted a plurality of times due to a situation in which an error easily occurs at the same timing.

Therefore, in the present invention, for the same GOB in an image frame, the transmission order of the MB data can be reversed by reversing the arrangement order of the MB data between one GOB and the other GOB. This allows
It is possible to prevent errors from being concentrated on the same MB data in the GOB. In this case,
The image transmission control means 13 provided in the transmission side apparatus 1 inverts the arrangement order of the MB data included in the other GOB with respect to the same GOB in the image frame, and uses these GOBs as transmission units. The transmitting means is constituted by transmitting the data to the transmission path 3 by the transmitting communication means 15 via the transmitting communication control means 14.

In the above-described embodiment, as the reconstructing process of the image frame performed by the receiving-side apparatus 2, normal MB data is selected from MB data received a plurality of times for the same portion in the image frame, and one Decoding of this image frame after reconstructing the image frame of
For example, after decoding a plurality of image frames from the MB data received a plurality of times, an MB that is normally decoded
Data can be selected to reconstruct one image frame. FIG. 7 shows a configuration example of the receiving apparatus 2 in this case. Note that the configuration of the transmission-side device 1 is the same as that in the above-described embodiment, and thus description thereof will be omitted in this embodiment.

As shown in the above embodiment, the receiving-side apparatus 2 shown in FIG. 2 includes a receiving-side communication unit 21, a receiving-side communication control unit 22, an image reception control unit 23, and an image decoding unit. 24, and an image output unit 25. In this example, the image error correction unit 2 further corrects an image error.
8 are provided. Note that the configurations of the receiving-side communication unit 21, the receiving-side communication control unit 22, and the image output unit 25 are the same as those in the above-described embodiment, and thus description thereof is omitted in this example.

As shown in FIG. 4, the image reception control unit 231, as in the above embodiment,
, A receiving-side temporary storage unit 232, an MB error detection result storage unit 233, and an alternative MB storage unit 234. The image reception control unit 231 includes a unit that stores a normal one of the MB data having the same image ID in the reception-side temporary storage unit 232 as in the case of the above-described embodiment. For the image frame, a process of storing the MB data transmitted a plurality of times from the transmission side apparatus 1 in the reception side temporary storage unit 232 as a separate frame for each transmission number is performed. For this reason, the receiving-side temporary storage unit 232
Has a configuration capable of storing and holding a plurality of image frames.

Here, as a method for detecting a change in the number of transmissions for the same image frame, for example, as in this example, the case where the MB data transmission order is the same between the first transmission and the second transmission Detecting that the number of transmissions has been switched, for example, from the first transmission to the second transmission, by detecting that the values of the group ID and the block ID of the received MB data have made one round. Can be. Further, for example, a configuration in which the switching of the number of transmissions is notified from the transmitting device 1 to the receiving device 2 or a configuration in which the transmitting device 1 adds an identifier indicating the number of transmissions to each MB data may be used. it can.

Similarly to the above, the image reception control unit 231 separately stores the group ID and the block ID of the normal MB data for each number of transmissions in the MB error detection result storage unit 233.
Notify. Therefore, the MB error detection result storage unit 233
Is configured to be able to store whether MB data for the same portion in an image frame has been normally obtained separately for each transmission count. The MB error detection result storage unit 233 is connected to the image error correction unit 28, and stores the in-image error position information indicating the error position of the MB data stored for each transmission count as described above. Notify.

Further, when the image ID of the MB data changes, the image receiving control unit 231
, Read out a plurality of MB data for the same image ID stored and held in the memory, assign substitute MB data to an image portion for which normal MB data was not obtained, and output the plurality of MB data Means are provided. The configuration of the alternative MB storage unit 234 is the same as that of the above embodiment.

The image decoding means 24 is a means for decoding the coded image frame in accordance with the coding method, as in the case of the above embodiment. In this example, the same image I
The configuration is such that a plurality of image frames input for D can be decoded simultaneously. In this example, the processing of a plurality of image frames is performed simultaneously by the image reception control means 23 and the image decoding means 24. However, for example, the processing timing is adjusted to adjust the processing timing of each image frame. A configuration in which the processing is sequentially performed may be adopted.

The image error correction means 28 is composed of, for example, a frame memory, stores and holds a plurality of image frames decoded for the same image ID, and selects normal MB data from the plurality of image frames. This is means for reconstructing one image frame. That is, in this example, the reconstructing means is constituted by the image frame reconstructing process performed by the image error correcting means 28.
In this reconstruction processing, for example, based on one image frame, a normal M
If the same part of the MB data has not been obtained and the MB data of the same part has been normally obtained in another image frame, the normal MB data is applied to the corresponding position in the base image frame. It performs processing such as going.

Note that the above processing is performed based on the error position information in the image notified from the MB error detection result storage unit 233 described above. That is, since the position of the MB data that could not be obtained normally by the image reception control means 23 can be grasped for each image frame, an image part which cannot be decoded normally by this can be identified for each image frame. Can be grasped.

Next, a description will be given, with reference to an example of a process shown in FIG. 8, of a process of reconstructing an image frame performed by the receiving-side apparatus 2 having the above configuration. In this example, as in the above-described embodiment, a case will be described in which the MB data for the same part in the image frame to be transmitted is transmitted twice. Note that the processing by the transmitting device 1 is the same as the processing shown in FIG. 5A described above. The receiving device 2 receives the first MB data transmitted from the transmitting device 1 for the same image frame (step S21), and
A normal one of the data is stored as the first image frame (step S22), and the second transmitted MB data is received (step S23).
A normal one of the B data is stored as a second image frame (step S24).

Then, the first image frame stored as described above is decoded (step S2).
5) Decode the second image frame (Step S)
26). Next, normal MB data is selected from the two decoded image frames to reconstruct one image frame (step S27), and the reconstructed image frame is output to the screen as a moving image. (Step S2
8). As described above, the receiving-side apparatus 2 can normally reproduce the image portion other than the error portion of the image that cannot be decoded normally in the first transmission and the second transmission. .

Therefore, for example, when only the first image frame 41 shown in FIG. 9A is transmitted, or when only the second image frame 42 shown in FIG. Even in the case where many image portions indicated by hatched portions are not normally reproduced, the normally decoded MB data is selected from the first image frame 41 and the second image frame 42 to select 1 MB. By reconstructing the image frames, it is possible to reproduce the image frame 54 in which the error part is reduced as shown in FIG. That is, as shown in FIG. 9C, the image part 53 that is not normally decoded in both image frames overlaps as shown in the image frame 53 in which the error part shown by the diagonally shaded part is superimposed on the two image frames. A normal image can be reproduced for a part which is not present, whereby high-quality image transmission can be realized by quick processing.

Further, as described above, the image frame reconstruction processing performed by the reception-side apparatus 2 includes decoding a plurality of image frames from MB data received a plurality of times for the same portion in the image frame. When the process of selecting normally decoded MB data and reconstructing one image frame is performed, only one encoding direction is used as the encoding performed for each GOB. Although the encoding process of the MB data is performed by using the encoding process described above, the encoding process of the MB data may be performed by using, for example, two encoding directions that are mutually inverted. FIG. 10 shows a configuration example of the image transmission system in this case. The image transmission system shown in the figure is provided with a transmission side device 1, a reception side device 2, and a transmission line 3 connecting these two devices, as in the case of the above embodiment.

As in the case of the above-described embodiment, the transmitting apparatus 1 includes an image input unit 11, an image encoding unit 12, an image transmission control unit 13, a transmission communication control unit 14, Means 15 are provided, and in this example,
Image encoding control means 16 for controlling image encoding processing
And a transmission-side image inverting unit 17 for inverting the image, and a second image encoding unit 18 for encoding the image. Note that the configurations of the image input unit 11, the image encoding unit 12, the transmission-side communication control unit 14, and the transmission-side communication unit 15 are the same as those in the above-described embodiment, and a description thereof will be omitted in this example.

The image coding control means 16 outputs the image frame to be transmitted to the image coding means 12 or
This is a means for outputting an image frame to be transmitted to both the image encoding means 12 and the transmission-side image inversion means 17, and a means for controlling the output timing and the like thereof.
The image frame to be transmitted is the image encoding control unit 1
6 is output only to the image encoding means 12,
As in the case of the above embodiment, transmission processing using only one encoding direction can be performed. The transmitting-side image inverting unit 17 is a unit for inverting an image frame. In this example, as shown in FIG. 11B, the input image frame 61 shown in FIG. 2
Each image portion is inverted with respect to the central axis 62 that is equally divided as a reference, and the image frame 63 shown in FIG. Here, in this example,
Since the GOB is composed of MB data arranged in the horizontal direction, the image frame is inverted left and right. However, any method may be used as the inversion method.
It suffices if the arrangement order of the MB data in the GOB can be reversed according to the method of OB configuration.

The second image coding means 18 is a means for coding an image frame, like the image coding means 12. The second image encoding unit 18 encodes the image frame inverted by the transmission-side image inversion unit 17 described above, that is, encodes the image frame in which the arrangement order of the MB data in each GOB is inverted. Become Therefore, for the same MB data in the same image frame, the encoding direction by the image encoding unit 12 and the encoding direction by the second image encoding unit 18 are opposite to each other. In this example, the image encoding means is configured by the image encoding means 12 or the second image encoding means 18 encoding the MB data using the correlation between the MB data in the encoding direction along the GOB. You.

The image encoding control means 16 outputs the same image frame to the image encoding means 12 and outputs the same image frame to the second image encoding means 18 via the transmission-side image inverting means 17, and By inverting the MB data constituting the frame in encoding directions that are inverted with respect to each other, an inversion encoding unit is configured. Here, in this example,
As means for encoding an image frame, two means, an image encoding means 12 and a second image encoding means 18, are separately provided. Accordingly, for example, H.264 encodes an image frame using inter-frame correlation such as a motion vector between frames or inter-frame prediction encoding (frame difference). 26
H.1 system Even when an encoding system such as the H.263 system is used, it is possible to prevent encoding based on frame correlation between an image frame that has not been inverted and an image frame that has been inverted. it can.

For this reason, when a method of encoding an image frame without using inter-frame correlation, such as the JPEG method, is used, either the image encoding means 12 or the second image encoding means 18 is used. Thus, both the image frame that has not been inverted and the image frame that has been inverted may be encoded. Note that the encoding method by the image encoding means 12 and the encoding method by the second image encoding means 18 are not necessarily the same. In this case, the encoding method of the image encoding means 12 And the decoding method of the image decoding means 24 described later, and the coding method of the second image coding means 18 corresponds to the decoding method of the second image decoding means 26 described later. Just do it.

The image transmission control unit 13 includes the transmission control unit 131 and the transmission-side temporary storage unit 13 as in the above embodiment.
In this example, the transmission control unit 131
Add each ID to the MB data coded without inverting the image and the MB data coded by inverting the image for the same image frame, and
The transmission-side temporary storage unit 132 separately stores an image frame whose data has not been inverted and an image frame whose data has been inverted.
To memorize. Here, in this example, the same ID is added to the MB data for the same part in the same image frame regardless of the encoding direction. In this example,
An identifier indicating the encoding direction is added to each MB data, so that it is possible to identify whether each MB data is data of a non-inverted image frame or data of an inverted image frame.

The transmission control unit 131 appropriately reads out and outputs the MB data stored in the transmission-side temporary storage unit 132, so that the MB data of the non-inverted image frame and the MB data of the inverted image frame are output. Can be transmitted any number of times. With the above configuration, the transmitting apparatus 1 encodes and transmits one of the MB data in the encoding direction along the GOB with respect to the same part of the MB data in each of the image frames constituting the input moving image. , The other M
The B data is encoded and transmitted in the encoding direction along the GOB in which the arrangement order of the MB data is reversed.

As in the case shown in FIG. 7 described above, the receiving device 2 includes a receiving communication means 21, a receiving communication control means 22, an image reception control means 23, and an image decoding means 24. , An image output unit 25, and an image error correction unit 28. In this example, a second image decoding unit 26 that decodes the image, a receiving-side image inversion unit 27 that inverts the image, Is provided. Here, the description of the same configuration as that shown in FIG. 7 is omitted, and in this example, the image reception control unit 23 and the second image decoding unit 26
And the receiving-side image reversing means 27 will be described.

The image reception control means 23 comprises an image reception control section 231, a receiving-side temporary storage section 232, an MB error detection result storage section 233, and an alternative MB storage section 234, as in the above embodiment. I have. The processing performed by these devices is the same as that described with reference to FIG. 7, but in this example, a plurality of MBs for the same image ID stored and held in the receiving-side temporary storage unit 232 are used. When reading and outputting the data, the non-inverted image frame is output to the image decoding unit 24, and the inverted image frame is output to the second image decoding unit 2
Output to 6.

The second image decoding means 26 is a means for decoding the coded image frame, similarly to the image decoding means 24. In this example, the second image decoding means 26 And decode the image frame. The second image decoding unit 26 and the above-described image decoding unit 24 constitute a decoding unit that decodes the encoded MB data in accordance with the encoding direction. The receiving-side image inverting unit 27 is the same unit as the transmitting-side image inverting unit 17 provided in the transmitting-side apparatus 1, and is inverted again by further inverting the image frame inverted by the transmitting-side apparatus 1. This is a means for outputting as a previous image frame.

Also in this example, as in the case shown in FIG. 7, the image error correction means 28 selects normal MB data from a plurality of image frames decoded for the same image ID. Reconstructing one image frame constitutes a reconstruction means. Here, this reconstruction processing is performed based on the intra-image error position information notified from the MB error detection result storage unit 233 as described above. In this example, the above-described reconstruction processing is performed after the image frame inverted by the transmitting apparatus 1 is inverted by the receiving apparatus 2 again. It may be performed without inversion, and in this case, the receiving-side image inverting means 27 may not be provided in the receiving-side device 2.

With the above configuration, the receiving apparatus 2 decodes the non-inverted image frame and the inverted image frame from the MB data received for the same image frame, and decodes the same image frame among the decoded image frames. One image frame is reconstructed by selecting normal MB data from a plurality of MB data for the portion. Next, an example of the image transmission processing performed by the above configuration will be described with reference to the drawings. In this example, a case will be described in which the image frame to be transmitted is transmitted once from the transmission-side apparatus 1 and the inverted image frame is transmitted once.

As shown in FIG. 5A, the transmitting side apparatus 1 inputs a moving image to be transmitted (step S1), and sequentially transmits each image frame constituting the input moving image. The image is encoded without inverting, and the image is inverted and encoded (step S2). Then, for these encoded image frames, first,
A plurality of coded MB data constituting the non-inverted image frame is transmitted to the transmission path 3 as the first transmission (step S3), and subsequently, an inverted image frame of the same image frame is formed. Multiple encodings M
The B data is transmitted to the transmission path 3 as the second transmission (step S4). In this way, the image data to be transmitted is transmitted twice from the transmission-side apparatus 1 in a non-inverted and an inverted image frame.

In the receiving apparatus 2, as in the case shown in FIG. 8, the same MB is encoded for the first non-inverted image frame transmitted from the transmitting apparatus 1. Upon receiving the data (step S21), a normal one of the encoded MB data is stored as the first image frame (step S22), and the code for the inverted image frame transmitted second time is stored. Receiving the modified MB data (step S2
3), among these coded MB data, a normal one is stored as a second image frame (step S24).

Then, the first image frame stored as described above is decoded (step S2).
5) The second image frame is decoded, and the second image frame is subjected to the inversion process again (step S2).
6). Next, normal MB data is selected from the two decoded image frames to reconstruct one image frame (step S27), and the reconstructed image frame is output to the screen as a moving image. (Step S2
8).

As described above, in the receiving apparatus 2, for example, on the basis of the first image frame, the portion of the basic image frame for which normal MB data has not been obtained is the second image frame. MB of the same part in the frame
If the data is normally obtained, the normal MB data in the second image is applied to the corresponding position in the first image frame, thereby performing the process.
Image portions other than the image portion that could not be decoded normally on the first and second images can be normally reproduced.

As described above, when the same MB data is encoded and transmitted in the encoding directions inverted from each other, the decoding directions of these MB data can be inverted from each other. For example, as shown in FIG. The direction of the image portion that cannot be decoded due to an error occurring in the non-inverted image frame 41 and the direction of the image portion that cannot be decoded due to the error occurring in the inverted image frame 72 And can be reversed. Here, in FIG. 12, for both image frames, image portions that cannot be decoded normally are indicated by hatched portions.

Thus, the image frame 74 in which the non-inverted image frame 41 and the inverted image frame 72 are superimposed again on the inverted image frame 72 has not been successfully decoded in both image frames. For the part where the part does not overlap, normal MB data can be selected to reconstruct the image frame 75, thereby realizing high-quality image transmission by quick processing.

In the present invention, each of the functional units 11 to 18 and each of the functional units 21 to 28 described above are configured by executing a control program on a hardware resource including, for example, a processor and a memory. Alternatively, for example, these functional units may be configured as independent hardware circuits. Further, the present invention provides a floppy disk or CD-ROM storing the above-mentioned control program.
The control program can be grasped as a storage medium such as a ROM, and the processing according to the present invention can be performed by inputting the control program from the storage medium to a computer and causing the processor to execute the control program.

In the above embodiment, MB data is used as block data and GOB is used as a block data string.
Although an example in the case of using the above is shown, these configurations are arbitrary. For example, MCU data may be used as block data, or a slice may be used as a block data sequence. Further, in the above-described embodiment, an example in which the MB data of the same part in the image frame is transmitted twice has been described. May be set based on the certainty, efficiency, and the like required for the system.

Further, in the above embodiment, the image transmission processing is performed for each image frame constituting the moving image. However, as a target of the processing according to the present invention, for example, a still image frame may be used. It suffices if processing can be performed for each frame. Further, in the above embodiment, the error detection is performed for each MB data. However, the error detection may be performed in units of a group of a plurality of MB data. Further, in the above embodiment, the MB data is transmitted using the frame format of the HDLC procedure, but any procedure may be used as the communication procedure.

Further, by using the present invention together with the retransmission method and the error correction method, more reliable image transmission processing can be performed. When the present invention and the retransmission method are used together,
For example, block data for the same portion in an image frame to be transmitted is transmitted a plurality of times from the transmitting device, and the receiving device cannot obtain an image of the required quality even with the plurality of received block data. In this case, a retransmission process can be requested to the transmitting device. As described above, by transmitting the same block data a plurality of times at a time, the transmitting device only needs to perform the confirmation process of the response signal for each of the plurality of transmission processes.
It is possible to reduce a delay in image transmission caused by this confirmation processing.

When the present invention and the error correction method are used together, the transmitting device transmits the block data of the same portion in the image frame to be transmitted a plurality of times, and the receiving device transmits, for example, one block. The error of the first image frame is corrected by the error correction code, and for the error exceeding the error correction capability, normal block data is selected from the second and subsequent image frames according to the present invention, and the first image frame is selected. Can be applied to In this case, as long as no error occurs in all of the same block data transmitted from the transmitting apparatus a plurality of times, normal block data can be selected to reconstruct an image frame.

[0075]

As described above, according to the image transmission system according to the present invention, the same block data in the image frame to be transmitted is transmitted from the transmitting device to the receiving device a plurality of times. Even in the case of occurrence, the receiving apparatus can select and reproduce normal data from these block data, thereby realizing high-quality image transmission by rapid processing. Further, the present invention provides the same block data sequence even when there is a situation where an error occurs at the same timing when transmitting a block data sequence obtained by combining a plurality of block data as a transmission unit. about,
Since the arrangement order of the block data included in the other block data sequence is inverted with respect to one block data sequence and transmitted, it is possible to prevent errors from being concentrated on the same block data. Can be.

According to the present invention, for the same block data sequence in an image frame to be transmitted, one block data sequence and the other block data sequence are coded by reversing the coding direction and then transmitted. , The decoding direction of these two block data strings can be inverted,
As a result, the receiving apparatus can reduce the rate of occurrence of a situation in which all of a plurality of block data received for the same part in an image frame are not correctly decoded, and high quality can be achieved by rapid processing. Image transmission can be realized.

[Brief description of the drawings]

FIG. 1 is a configuration example of an image transmission system according to an embodiment of the present invention.

FIG. 2 is a diagram for explaining encoding of MB data and IDs of MB data.

FIG. 3 is a diagram illustrating a configuration of an image transmission control unit.

FIG. 4 is a diagram illustrating a configuration of an image reception control unit.

FIG. 5 is an example of a process when the same MB data is transmitted twice.

FIG. 6 is a diagram for explaining an example of image frame reconstruction processing.

FIG. 7 is a configuration example of a receiving-side device.

FIG. 8 is an example of a process in a receiving device.

FIG. 9 is a diagram for explaining an example of image frame reconstruction processing.

FIG. 10 is a configuration example of an image transmission system according to an embodiment of the present invention.

FIG. 11 is a diagram illustrating an image inversion process.

FIG. 12 is a diagram for explaining an example of image frame reconstruction processing.

FIG. 13 is a diagram for describing an encoding process between block data.

FIG. 14 is a diagram for explaining an error that has occurred during the decoding process.

[Explanation of symbols]

1 .... Transmission side device, 2 .... Reception side device, 3 .... Transmission path, 11 ... Image input means, 12 ... Image encoding means, 13 ... Image transmission control means, 14 .... Transmission side communication control Means, 15... Transmission side communication means, 16... Image coding control means, 17... Transmission side image inversion means, 18.
Second image encoding means, 21 communication means on the receiving side;
22: receiving side communication control means, 23: image receiving control means, 24: image decoding means, 25: image output means, 26: second image decoding means, 27: receiving side image inversion Means, 28... Image error correction means, 131.
A transmission control unit, 132, a temporary storage unit on the transmission side, 231
..Image reception control section, 232..Reception side temporary storage section,
233... MB error detection result storage unit, 234.

Claims (3)

[Claims] An image transmission system that divides an image frame to be transmitted into a plurality of block data and sequentially transmits the block data from a transmitting device to a receiving device. A transmitting unit for transmitting the block data of the portion two or more times set in advance; and a receiving device for receiving the block data and a plurality of block data received for the same portion in the image frame. Reconstructing means for reconstructing the image frame by selecting normal block data. An image transmission system comprising: 2. The image transmission system according to claim 1, wherein the transmission unit transmits a block data sequence obtained by combining a plurality of block data as a transmission unit, and transmits one of the block data sequences in the image frame. An image transmission system, wherein the sequence of block data included in the other block data sequence is inverted with respect to the block data sequence and transmitted. 3. The image transmission system according to claim 1, wherein the transmitting apparatus collects a plurality of block data into a block data sequence, and converts the block data in a coding direction along the block data sequence. Coding means for coding using the correlation between the coding means, and for the same block data string in the image frame, one of the block data strings is coded by the coding means and the other block data string is coded in the coding direction. Further comprising an inversion encoding means for inverting and encoding by the encoding means, wherein the transmission means transmits the encoded block data; and A decoding unit that decodes the block data in accordance with the encoding direction, wherein the reconstructing unit corrects the block data from the decoded block data. An image transmission system, characterized in that selecting a block data.