JPH09182070A - Image communication method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To transmit images with high efficiency and in a short time even via a communication path having a large error rate by transmitting only the contour block of an image with encoding of an information source to transmit it again as necessary and then interpolating the non-contour block of the image based on the contour data at the receiving side. SOLUTION: A contour block discriminator 13 decides the contours on every screen and outputs first a contour decision table to a communication control part 4 to show the contour decision results to make the part 4 send the decision table to a communication path together with an error detection code. Then only the image data on a contour block are sent to the communication path in the same way through the discrete cosine conversion, quantization, Huffman coding and addition of error detection code. At the receiving side, the error detection is carried out by an error detection decoder 9 of a communication control part 8. If an error is detected, a retransmission request is transmitted. If no error is detected, a contour block discriminator 14 stores the contour image data which are successively sent to a proper memory position of an interpolator 15 based on the information on the contour decision table and then performs the interpolation for the pixel value of the block that includes no contour.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image communication method for compressing and transmitting an image, and in particular, an image communication capable of efficiently transmitting an image while maintaining a certain degree of accuracy even in a communication path with poor line quality. Regarding the method.

[0002]

2. Description of the Related Art First, a conventional image communication apparatus is shown in FIG.
I will explain using. FIG. 7 is a configuration block diagram of a conventional image communication device. As shown in FIG. 7, a conventional image communication device has a discrete cosine transformer 1 and a quantizer 2 on the transmitting side.
And a Huffman encoder 3, a communication control unit 4 having an error detection encoder 5 inside, and a modulator 6, and the receiving side has a demodulator 7 and an error detection decoder 9 inside. It is composed of a communication control unit 8, a Huffman decoder 10, an inverse quantizer 11, and an inverse discrete cosine transformer 12, and the transmitting side and the receiving side are connected via a communication path.

Next, each section of the conventional image communication apparatus will be described. The discrete cosine transformer 1 converts the digitally converted input image data into an encoded block (for example, 8 × 8 pixels or 16 × 16 pixels, hereinafter simply referred to as a block).
Discrete Cosine Transform (DC)
T) Transform coding is performed to transform and output DCT coefficients. The quantizer 2 quantizes the DCT coefficient transform-coded by the discrete cosine transformer 1 to output a quantized coefficient in which the number of effective coefficients is reduced. The Huffman encoder 3 entropy-encodes the quantized coefficients quantized by the quantizer 2 and outputs information source encoded data (encoded data). As an example of entropy encoding, Huffman encoding is performed. It has been known.

The error detection encoder 5 adds an error detection code for detecting a transmission error to the encoded data output from the Huffman encoder 3. An example of the error detection code is an error detection code. There is a CRC (Cyclic Redundancy Checks) code that is known to be able to detect both independent errors that occur independently and burst errors that occur continuously, and the generator polynomial of the CRC is generally ITU-T x ¹⁶
+ X ¹² + x ⁵ +1 is used. Details regarding CRC are described in "Computer Communication and Network", Kunio Fukunaga, Kyoritsu Shuppan Co., Ltd., pp. 78-82.

The communication control section 4 incorporates the data to which the error detection code is added by the error detection encoder 5 into a transmission frame according to the transmission control procedure and outputs the data to the modulator 6. Note that one or more blocks of information source encoded data are incorporated in one transmission frame.

Here, an example of the transmission control procedure is a synchronous procedure in which variable length data can be transmitted in bit units and a highly reliable transmission can be performed by issuing a retransmission request when an error is detected. HDLC (High level Data Link)
Control) procedure is common.

As shown in FIG. 8, a transmission frame, which is a transmission unit in the HDLC procedure, has a flag for detecting the start of the frame, an address of the transmission destination, and a control for setting a command or response according to the procedure. , Variable length data to be transmitted, that is, image data (source coded data) here, and error correction code (here C
(RC code) and a flag for detecting the end of the frame. FIG. 8 is an explanatory diagram showing a transmission frame format of the HDLC procedure. HDLC
Details of the procedure are described in “Computer Communication and Network”, Kunio Fukunaga, Kyoritsu Shuppan Co., Ltd., p113-p130.

In the HDLC procedure, when a frame-side error is detected on the receiving side, a retransmission request is transmitted. Therefore, the error detection encoder 5 responds to the retransmission request from the receiving side. The frame retransmitting operation is also performed.

The modulator 6 modulates transmission data into a signal suitable for a communication path and sends it out to the communication path. Demodulator 7
Is to demodulate the transmission data received from the communication path and output it to the communication control unit 8.

The error detection decoder 9 detects an error in the demodulated received data. The communication control unit 8 performs a process according to the communication control procedure, and when an error is detected, the communication control unit 8 transmits a retransmission request according to the HDLC procedure and exchanges data until error-free data can be received. ing. Then, for data having no error, the Huffman decoder 10 extracts the source coded data portion.
Is output to

The Huffman decoder 10 entropy-decodes error-free coded data received from the communication controller 8 and outputs quantized coefficients, and the inverse quantizer 11 outputs the Huffman decoder 10. Are inversely quantized to output DCT coefficients. The inverse discrete cosine transformer 12 inversely discrete cosine transforms the DCT coefficients from the inverse quantizer 11 to obtain an image decoded by the information source. It outputs data.

Next, the operation of the conventional image communication apparatus will be described with reference to FIG. In a conventional image communication apparatus, when image data of an image to be transmitted is input to a transmission side, the discrete cosine transformer 1 performs discrete cosine transform, the quantizer 2 quantizes, and the Huffman encoder 3 entropy code. Information source coded, and further communication control unit 4
In (1), the error detection code is added by the error detection encoder 5, incorporated into the HDLC frame, modulated by the modulator 6, and sent to the communication path.

On the receiving side, the data received from the communication path is demodulated by the demodulator 7, the error is detected by the error detection decoder 9 in the communication control unit 8, and a retransmission request is made for the frame in which the error is detected. Is transmitted to the transmission side via the demodulator 7, and the communication control unit 4 which has received the retransmission request via the modulator 6 retransmits the frame for which the retransmission request has been made. Further, for the frame in which no error is detected by the error detection decoder 9 in the communication control unit 8, the information source coded data portion is taken out, entropy-decoded by the Huffman decoder 10, and dequantized by the dequantizer 11. Inverse quantization is performed, inverse discrete cosine transform is performed by the inverse discrete cosine transformer 12, information source decoding is performed, and image data is output.

[0014]

However, in the above-mentioned conventional image communication apparatus, when an image is transmitted through a communication path having a large error rate such as wireless communication, the frequency of re-transmission is high and the communication time becomes very long. There was a problem that it was not appropriate.

The present invention has been made in view of the above circumstances, and provides an image communication method capable of efficiently transmitting an image in a short time while maintaining a certain degree of accuracy even in a communication path having a large error rate. The purpose is to

[0016]

According to a first aspect of the present invention for solving the above-mentioned problems of the conventional example, in the image communication method, an original image is divided into coding blocks on the transmitting side, and the coding blocks are divided. For each of the contour blocks, it is determined whether or not it is a contour block, and only the contour block is transmitted by adding an error detection code to the information source coded data obtained by performing the information source coding. When it is detected, it is retransmitted, the information source coded data that is normally received is information source decoded, the contour block is reproduced, and the portion other than the reproduced contour block is reproduced by interpolation, and the data to be transmitted. An image can be efficiently transmitted in a short time while reducing the amount and maintaining a certain degree of accuracy even in a communication path with a large error rate.

According to a second aspect of the present invention for solving the problems of the conventional example, in the image communication method, an original image is divided into coding blocks on the transmitting side, and a contour including a contour for each of the coding blocks. Blocks and non-contoured blocks that do not include contours are selected, and all source coded blocks are transmitted by adding error detection codes to the source coded data obtained by source coding. If it is detected, it is judged whether it is the source coded data of the contour block or the source coded data of the non-contour block, and if it is the source coded data of the contour block, it is retransmitted and the contour block of the normally received contour block is judged. The feature is that the source block is reproduced by decoding the information source coded data and the contour block is reproduced in the case of the non-contour block information source coded data, and the retransmission frequency is reduced and the error rate is reduced. While retaining the larger channel at a certain accuracy even, it can be transmitted efficiently images in a short time.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the claimed invention will be described with reference to the drawings. According to a first image communication method of the present invention, a block including a contour is extracted from an original image in coding block units, only the block including the contour is source-coded, error-detection-coded and transmitted, and an error is detected. If so, it retransmits, and after the source decoding, it interpolates the block portion that does not include the contour.Therefore, by limiting the data to be transmitted to the block that includes the contour, the amount of transmission data is greatly reduced. However, the others can be compensated by interpolation, and the transmission efficiency can be improved while maintaining a certain degree of accuracy of the reproduced image.

First, the configuration of an image communication apparatus (first apparatus) for implementing the first image communication method according to the present invention will be described with reference to FIG. FIG. 1 is a block diagram showing the configuration of an image communication apparatus for realizing a first image communication method according to the present invention. Parts having the same configuration as in FIG. 7 will be described with the same reference numerals.

The first apparatus of the present invention is basically the same as the conventional image communication apparatus shown in FIG. 7, and has a discrete cosine transformer 1, a quantizer 2, and a Huffman encoder on the transmission side. 3 and a communication control unit 4 having an error detection encoder 5
And a modulator 6, and a receiving side includes a demodulator 7, a communication control unit 8 having an error detection decoder 9, a Huffman decoder 10, an inverse quantizer 11, and an inverse discrete cosine transformer. 12 and further as a characteristic part of the present invention,
A contour block selector 13 is provided on the transmitting side, and a contour block selector 14 and an interpolator 15 are provided on the receiving side.

Next, each part of the first device will be specifically described. The discrete cosine transformer 1, the quantizer 2, and
Huffman encoder 3, error detection encoder 5, modulator 6, demodulator 7, error detection decoder 9, Huffman decoder 10, inverse quantizer 11, and inverse discrete cosine Since the converter 12 is completely the same as the conventional one, its explanation is omitted here.

The contour block selector 13 performs contour selection for selecting the original image in coding block units into coding blocks (contour blocks) including a contour and coding blocks (non-contour blocks) not including a contour. It is a thing. Specifically, the contour block selector 13 stores the image data of the input original image for one screen, determines whether or not it is a contour block on a coding block basis, and replaces the determination result with a value. When the table is created and the determination for one screen is completed, the contour determination table is first output to the communication control unit 4, and then only the image data of the contour block is determined in a predetermined order (for example, left to right, top). From the downward direction) to the discrete cosine converter 1.

Here, as a method of determining the contour block, a generally known method such as a Laplacian operator is used, and from the pixel value distribution l (x, y) of the original image, as an example, the kernel of the filter shown in FIG. Using h (k, l), the contour image E (x, y) is obtained by the following equation. E (x, y) = ΣΣl (x + k, y + l) * h (k, l) However, in the case of FIG. 2 (a), k, l = -1,0,1 and in FIG. 2 (b) If
k, l = -2, -1,0,1,2 Note that the process for obtaining the contour image is RG if it is a color image.
Only one component of B or one component of the luminance component when converted into luminance (Y) and color difference (Cr, Cb) may be performed. FIG. 2 shows the kernel h of the filter used in the first device.
FIG. 4 is an explanatory diagram showing a specific example of (k, l).

Then, for each coded block of the original image, the corresponding contour image E is examined, and if there are 10 or more pixels with large pixel values adjacent to each other, it is determined to be a contour block. Is determined.

The contour judgment table is a table showing the judgment result of the contour for each coded block, and is, for example, 640 × 480.
When a pixel image is encoded and transmitted in 16 × 16 pixel block units, if the determination result of each encoded block is represented by 1 bit and the portion including the contour is represented as 1 and the portion not including the contour is represented as 0, the contour is The size of the judgment table is 1200 bits.

The communication control unit 4 includes a contour block selector 13
From the Huffman encoder 3 and the encoded data of the contour block from the Huffman encoder 3 are subjected to error detection encoding by the error detection encoder 5 to create a transmission frame according to the same HDLC transmission control procedure as the conventional one. And outputs it to the modulator 6.

The communication control unit 8 performs error detection on the transmission frame demodulated by the demodulator 7 by the error detection decoder 9, and if an error is detected, sends a resend command via the demodulator 7. . Then, when no error is detected, the contour determination table is output to the contour block selector 14, and the encoded data of the image is output to the Huffman decoder 10.

The contour block selector 14 stores the image data decoded by the inverse discrete cosine converter 12 at an appropriate position. Specifically, the contour block selector 14 outputs the contour judgment table output from the communication controller 8. When the image data is stored and the image data is received in block units from the inverse discrete cosine transformer 12, the position of the value 1 indicating that the block is a contour block in the same order as the information source coding on the transmission side on the stored contour determination table. Is searched and the image data is stored in the corresponding block position of the internal memory of the interpolator 15.

The interpolator 15 interpolates image data of blocks other than the contour block from the received image data of the contour block, and has an internal memory for storing one screen of image data.

Here, an example of the interpolation processing will be described with reference to FIG. FIG. 3 is an explanatory diagram showing an example of an interpolation processing method in the image communication apparatus of the present invention. An example of the interpolation processing method is that the pixel value x of a block that does not include a contour (an example of a block of 8 × 8 pixels in the gray portion in FIG. 3) is the pixel values a, b, and c of 4 pixels around the received contour block. , D is used to calculate by the mathematical expression [Equation 1].

[0031]

[Equation 1]

The interpolation method is not limited to this example, and a simple method of copying the pixel values of adjacent blocks to a curve interpolation using a curve formula to calculate the interpolation method depending on the processing speed and interpolation accuracy. Any method may be used as long as is selected.

Next, the operation of the first image communication apparatus of the present invention will be described with reference to FIG. First of the present invention
Image communication device, the image to be transmitted to the sender (original image)
When the image data of is input, the contour block selector 13
One screen is stored, the contour judgment is made in coding block units, a contour judgment table showing the judgment result for one screen is output to the communication control unit 4, and the error detection encoder 5 is used in the communication control unit 4. The data is error-detection-encoded, embedded in an HDLC frame, modulated by a modulator 6, and transmitted to a communication path.

On the other hand, with regard to the image data for which the contour judgment has been completed by the contour block selector 13, only the image data of the contour block is sequentially output to the discrete cosine transformer 1, which is discrete cosine transformed by the discrete cosine transformer 1 and quantized. Is quantized by the device 2, entropy coded by the Huffman coder 3, error detection coded by the error detection coder 5 in the communication control unit 4, embedded in the HDLC frame, and modulated by the modulator 6. It is sent to the communication channel.

The contour determination table and the image data of the contour block sent from the transmitting side are demodulated by the demodulator 7 on the receiving side, and error detection is performed by the error detecting decoder 9 in the communication control section 8, When an error is detected, a resend command is transmitted via the demodulator 7, and the communication control unit 4 that has received the resend command via the modulator 6 resends.

On the other hand, if no error is detected by the error detection decoder 9, the contour judgment table is output to the contour block selector 14 and stored therein, and the coded data of the image is entropy by the Huffman decoder 10. Decoded, inverse quantized by the inverse quantizer 11, and inverse discrete cosine transformer 12
The image data is output to the contour block selector 14 after being subjected to inverse discrete cosine transform and information source decoding.

Then, the contour block selector 14 stores the image data in an appropriate position in the internal memory of the interpolator 15 in accordance with the information of the contour determination table, and the contour block for one screen is stored. Interpolation is performed for pixel values of blocks that do not include contours.

A comparison between the case of transmitting an image using the first image communication method of the present invention and the conventional method in terms of the error rate of the communication path and the communication time is shown in FIG. To
In the case of the first image communication method of the present invention, it can be seen that the communication time is reduced as a whole, and that the communication time is considerably shorter than that of the conventional method, especially in a place where the error rate is large. FIG. 4 is an explanatory diagram showing the relationship between the error rate of the communication path and the communication time.

According to the first image communication method of the present invention, the contour block is selected from the original image, only the contour block is subjected to the source coding and the error detection coding and transmitted, and the error is detected on the receiving side. In this case, since the data is reliably transmitted by retransmitting it, there is an effect that the amount of data to be transmitted can be significantly reduced and the communication time can be shortened.

Further, according to the first image communication method of the present invention, when the contour block is selected from the original image, the contour judgment table is created and transmitted, and the receiving side receives the contour judgment table using the contour judgment table. Since the contour block is restored to the proper position and the part other than the contour block is reproduced by interpolation from the contour block, only the important contour part is reliably transmitted by retransmission, and the other parts are not transmitted and the communication time Is significantly shortened and reproduced by interpolation, so that there is an effect that an image can be efficiently transmitted in a short time while maintaining a certain degree of accuracy even in a communication path with a large error rate.

Next, the second image communication method according to the present invention will be described. A second image communication method according to the present invention is
Blocks (contour blocks) and contour blocks (contour blocks) containing contours are selected from the original image in units of coded blocks, and the others (non-contour blocks) are source coded, error-detecting coded, and transmitted. If an error is detected, it is retransmitted, and if an error is detected on the receiving side for non-contour blocks, it is interpolated from surrounding pixels after information source decoding, so while maintaining the accuracy of the reproduced image to some extent. The transmission efficiency can be improved.

First, the configuration of the image communication apparatus (second apparatus) for realizing the second image communication method according to the present invention will be described with reference to FIG. FIG. 5 is a block diagram of the configuration of an image communication apparatus that realizes the second image communication method according to the present invention. Note that parts having the same configuration as in FIG. 1 are described with the same reference numerals.

The second device of the present invention is the first device shown in FIG.
The configuration of the first image communication device is basically the same as that of the first image communication device, except that the contour block selector 13 ', the communication control unit 4', the communication control unit 8 ', and the interpolator 15' are the same. Is different from.

Next, each part of the second device will be specifically described, but the description of the same parts as those of the first device will be omitted.
Only different parts will be described. Contour block selector 13 '
Is to perform contour selection to select the original image into coding blocks including contours (contour blocks) and coding blocks not including contours (non-contour blocks) in units of coding blocks. Image data of the input original image is 1
The screen is stored, it is determined whether or not the block is a contour block in coding block units, a contour determination table in which the determination result is replaced with a value is created, and when the determination for one screen is completed,
First, the contour determination table is output to the communication control unit 4, and subsequently, in a predetermined order in units of coding blocks (for example, from left to right,
The image data is output to the discrete cosine converter 1 from top to bottom). Note that the method of determining whether or not it is a contour block and the contour determination table are exactly the same as those of the first image communication apparatus, so description thereof will be omitted here.

The communication control unit 4'performs communication control on the transmission side. Specifically, the contour judgment table from the contour block selector 13 is error-detected and coded by the error-detection encoder 5, and the transmission frame is transmitted. Is generated and output to the modulator 6, and subsequently, a number (block number) indicating the position in the image is added to the encoded data from the Huffman encoder 3, and the error detection encoder 5 performs error detection. HDL as encoded
The transmission frame is created according to the C transmission control procedure and is output to the modulator 6.

The communication control section 8'performs communication control on the receiving side. Specifically, first, the error detection decoder 9 performs error detection on the transmission frame of the contour judgment table demodulated by the demodulator 7. If an error is detected, a resend command is sent via the demodulator 7, and if no error is detected, the contour judgment table is stored in the communication control unit 8'and the contour block selector It outputs to 14.

Then, with respect to the transmission frame of the image data demodulated by the demodulator 7, it is judged whether the contour block is a non-contour block by referring to the contour judgment table. In the case of the contour block, the error detection decoder 9 is used. Error detection is performed, and if an error is detected, a retransmission command is sent via the demodulator 7, and if no error is detected, the encoded data of the image is output to the Huffman decoder 10. Has become.

On the other hand, when the received transmission frame is a non-contour block, the error detection decoder 9 performs error detection,
If an error is detected, the data is discarded, and instead, the block number in which the error has occurred is obtained from the block numbers of the blocks normally received before and after, and the block number is output to the interpolator 15 'as error information. There is.

The interpolator 15 'interpolates the image of the non-contoured block in which an error has occurred, from the normally received image data of the surroundings, based on the error information from the communication control section 8'. It has an internal memory for storing data. Here, the interpolation method is the same as that of the first image communication apparatus, and therefore its explanation is omitted.

Next, the operation of the second image communication apparatus of the present invention will be described with reference to FIG. Second of the present invention
Image communication device, the image to be transmitted to the sender (original image)
When the image data of is input, the contour block selector 1
3'is stored for one screen, and contour judgment is performed in coding block units to select contour blocks and non-contour blocks. Then, a contour determination table showing the contour determination result for one screen is output to the communication control unit 4 ', and the communication control unit 4'.
At the error detection encoder 5 at H.
It is incorporated in the DLC frame, modulated by the modulator 6, and sent to the communication path.

Image data is output from the contour block selector 13 'to the discrete cosine transformer 1 in a predetermined order (for example, left to right, top to bottom) in units of coding blocks, and the discrete cosine transformer 1 is supplied. Is subjected to discrete cosine transform in step 1, is quantized in the quantizer 2, is entropy coded in the Huffman encoder 3, and is output to the communication controller 4.

Then, a block number is added to the encoded data from the Huffman encoder 3 in the communication control unit 4 ', and error detection encoding is performed in the error detection encoder 5 to obtain the HDL.
It is incorporated in the C frame, modulated by the modulator 6, and sent to the communication path.

On the receiving side, first, the transmission data of the contour judgment table is demodulated by the demodulator 7 on the receiving side, and the error is detected by the error detection decoder 9 in the communication control section 8 ', and an error is detected. In this case, the retransmission command is transmitted via the demodulator 7, and the communication control unit 4 that has received the retransmission command via the modulator 6 retransmits. On the other hand, when the contour determination table is normally received, it is stored in the communication control unit 8'and is output to the contour block selector 14 and stored therein.

Subsequently, the coded data of the image is demodulated by the demodulator 7, and it is judged whether or not it is a contour block by referring to the stored contour judgment table. Further, the error detection decoder 9 detects an error. Then, if the encoded data is a contour block, a retransmission command is transmitted through the demodulator 7, and if it is a non-contour block, the data is discarded and error information is output to the interpolator 15 '. To be done. On the other hand, if no error is detected in the encoded data of the image, the Huffman decoder 10 performs entropy decoding, and the inverse quantizer 1
1 is inversely quantized, an inverse discrete cosine transformer 12 inversely cosine transforms the information source, and image data is output to the contour block selector 14.

Then, the contour block selector 14 stores the image data in an appropriate position in the internal memory of the interpolator 15 'in accordance with the information of the contour determination table, and when the contour block for one screen is stored, the interpolator At 15 ', interpolation is performed on the pixel value of the non-contour block having an error based on the error information.

A comparison between the case of transmitting an image using the second image communication method of the present invention and the conventional method in terms of the error rate of the communication path and the communication time is shown in FIG. To
It can be seen that in the case of the second image communication method of the present invention, the communication time is considerably shorter at a place where the error rate is large as compared with the conventional method. FIG. 6 is an explanatory diagram showing the relationship between the error rate of the communication path and the communication time.

According to the second image communication method of the present invention, the contour block and the non-contour block are selected in the original image, the contour block retransmits for an error, and the non-contour block for an error. Since the interpolation is performed from the surrounding pixels after decoding the information source, the important contour part is reliably transmitted by retransmission, and the other parts are reproduced by interpolation even if an error occurs, so the overall communication time can be shortened. Even if the communication path has a high rate, it is possible to efficiently transmit an image in a short time while maintaining a certain degree of accuracy.

[0058]

According to the first aspect of the present invention, only the contour block of the original image is source-coded and transmitted, and if an error is detected on the receiving side, it is retransmitted, and after the source decoding, the contour block is transmitted. Since it is an image communication method that interpolates other parts, the amount of transmission data can be reduced, and non-transmission parts can be compensated by interpolation, and even in a communication path with a large error rate,
There is an effect that images can be efficiently transmitted in a short time while maintaining a certain degree of accuracy.

According to the second aspect of the present invention, the contour block of the original image is retransmitted when an error is detected, and the non-contour block is interpolated when an error is detected. The error of the non-contour block can be compensated by interpolation, and an image can be efficiently transmitted in a short time while maintaining a certain degree of accuracy even in a communication path having a large error rate.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of an image communication device that implements a first image communication method according to the present invention.

FIG. 2 shows the kernel h (k, k of the filter used in the first apparatus.
It is explanatory drawing which shows the specific example of l).

FIG. 3 is an explanatory diagram showing an example of an interpolation processing method in the image communication apparatus of the present invention.

FIG. 4 is an explanatory diagram showing a relationship between an error rate of a communication path and communication time.

FIG. 5 is a block diagram showing the configuration of an image communication apparatus that implements a second image communication method according to the present invention.

FIG. 6 is an explanatory diagram showing a relationship between an error rate of a communication path and communication time.

FIG. 7 is a configuration block diagram of a conventional image communication device.

FIG. 8 is an explanatory diagram showing a transmission frame format of an HDLC procedure.

[Explanation of symbols]

1 ... Discrete cosine transformer, 2 ... Quantizer, 3 ... Huffman encoder, 4, 4 '... Error detection encoder, 5 ...
Error detection encoder, 6 ... Modulator, 7 ... Demodulator,
8, 8 '... Communication control unit, 9 ... Error detection decoder, 1
0 ... Huffman decoder, 11 ... Inverse quantizer, 12 ...
Inverse discrete cosine converter, 13, 13 ', 14 ... Contour block selector, 15, 15' ... Interpolator

Claims (2)

[Claims] 1. An original image is obtained by dividing an original image into coding blocks on a transmitting side, determining whether each coding block is a contour block including a contour, and performing source coding on only the contour block. The error detection code is added to the information source coded data and transmitted, and when an error is detected on the receiving side, it is retransmitted, and the information source coded data that is normally received is information source decoded to reproduce the contour block, An image communication method, wherein a portion other than the reproduced contour block is reproduced by interpolation. 2. An original image is divided into coding blocks on the transmission side, and each coding block is divided into a contour block including a contour and a non-contour block not including a contour, and all the coding blocks are source coded. Error detection code is added to the information source coded data obtained by the coding and transmitted, and if an error is detected on the receiving side, the information coded source of the contour block or the information source code of the non-contoured block Data,
In case of source coded data of contour block, it is retransmitted,
An image communication method, characterized in that information source coded data of a normally received contour block is subjected to information source decoding to reproduce a contour block, and in the case of non-contour block information source coded data, reproduction is performed by interpolation.