JPH10327413A - Image coding method and device, image decoder, image encoding decoding device, intra-coding control method and ratio image communication terminal equipment conducting intra-coding control processing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a deteriorated image recovery time in a method using a cycle refresh. SOLUTION: An important are discrimination section 105 discriminates whether or not a macro block is included in an important area. The macro block included in the important area is stored in an important are memory 106 as an important area till the macro block is refreshed for a prescribed number of times or over. The macro block stored in the important area memory is used for an object of intra-refresh. Thus, even in the case that the image quality of the macro block included in the important area is deteriorated, the deterioration is recovered in a short time and deterioration of the image quality of a block in a preceding important area no longer remains.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image encoding method and apparatus for a digital moving image signal, and an image decoding apparatus for use in a videophone, a video conference, etc., and particularly for performing image restoration using intra-encoding. The present invention relates to an image decoding / decoding device, an intra-encoding control method, and a wireless image communication terminal device that performs an intra-encoding control process.

[0002]

2. Description of the Related Art A conventional digital video signal encoding method is described in ITU-T Recomm, recommended in March 1993.
endation H.261.

[0003] H.261 is an encoding system composed of the following three element technologies.

The first is a motion compensation prediction method. The input picture and the pre-coded picture are compared, and the amount of motion between them is measured (motion detection). An input picture is predicted from the motion amount and the pre-coded picture. By calculating the difference (prediction error signal) between the predicted image (prediction image) and the input image picture, and transmitting the prediction error signal and the above-described motion amount to the receiving side, image information can be transmitted with a small data amount. I do.

[0005] The second is a discrete cosine transform. The aforementioned prediction error signal is transformed into the frequency domain. When a prediction error signal is converted into a frequency domain, power is concentrated in a specific frequency domain (low frequency domain). By utilizing this feature and combining with the third method described below, image information can be transmitted with a smaller data amount.

The third is a variable length coding system. This uses the fact that the power is biased to a specific frequency,
By expressing coefficients of frequencies with high appearance frequency with short code length and coefficients of frequencies with low appearance frequency with long code length,
This is a method for shortening the average code length. By using this, image information can be transmitted with a small amount of data.

The above three element technologies are not applied to the entire image picture, but are applied to each macroblock obtained by dividing the picture into blocks (macroblocks) of 16 * 16 pixels.

Further, there are the following two elemental techniques as techniques for suppressing image quality deterioration due to transmission errors.

The first is cyclic refresh intra coding. In this method, as shown in FIG. 8, intra coding without using the above-described predictive coding is performed on a plurality of macro blocks in one picture. Intra coding is not a method of coding a prediction error using a previous picture, but a method of performing discrete cosine transform of the pixel value of the current macroblock as it is and performing variable length coding. Therefore, even if a transmission error occurs in the previous picture and image quality deteriorates, the transmission of the transmission error can be prevented by transmitting the intra-coded macroblock. Cyclic refresh intra coding is a technique for preventing image quality deterioration by periodically performing intra coding of a plurality of macro blocks among macro blocks included in one picture.

The second is the group of blocks (GO)
B). This is a method of transmitting encoded data of a plurality of macroblocks as one synchronization unit. H.
261 will be described as an example. QCIF (Quarter Common Input Format) is used as the format of the input image. In QCIF, a luminance signal is 176 × 144 pixels and a color difference signal is 88 × 72 pixels, and is divided into 11 × 9 macroblocks.

The GOB is composed of 11 horizontally continuous macroblocks as one synchronization unit, with a synchronization word and a header added to the beginning (see FIG. 9). By configuring a plurality of macroblocks as one synchronization unit in this way, even when a transmission error occurs, the effect of the transmission error can be suppressed to this GOB, and does not spread to other GOBs.

[0012]

SUMMARY OF THE INVENTION Conventional cyclic
In the refresh method, the number of macroblocks encoded in one picture is M, and the number of macroblocks included in one picture is N. It takes N / M pictures until one entire picture is refreshed. Therefore, once the effect of a transmission error appears on the screen, it takes a long time to be refreshed, and the portion where the image quality has deteriorated is displayed on the screen for a long time.
There is a problem of.

Further, since the prediction coding method is used,
In a moving part, the part where the image quality has deteriorated spatially spreads over time.

In order to recover a deteriorated image portion in a short time, there is a method in which it is determined whether or not a macroblock is included in an important area in a screen, and only the macroblock determined to be important is intra-coded. In such a method, consider a case where an important area moves with time. In FIG. 10, the upper part is a coded picture, and the lower part is a picture decoded on the receiving side. The shaded portions are determined to be important regions and are intra-coded portions. In the first picture shown in the lower part of FIG. 1, a black portion of the intra-coded macroblock is
Indicates that the image quality has deteriorated due to a transmission error. When the important area in the second picture moves to the lower right, the part having deteriorated image quality remains without being refreshed. This portion has a problem that it remains until it is determined as an important region again.

It is an object of the present invention to recover the image quality deterioration of the important area in a short time and to prevent the image quality deterioration of the part which was the important area in the past from remaining.

A second problem is that a cyclic
Consider a scheme that combines refresh and synchronization units such as GOB. FIG. 11 shows the positions of intra-coded macroblocks and the structure of the GOB. GOB
Are determined in a horizontally continuous order, and intra-coded macroblocks are also
Like GOB, they are determined in a continuous order in the horizontal direction.

Therefore, when a transmission error occurs in one GOB, all the intra-coded macro blocks included in the GOB are lost. As a result, there is a problem that it takes time to recover the portion where the image quality has deteriorated.

It is an object of the present invention to minimize the number of macroblocks that are refresh intra-coded and lost due to transmission errors.

[0019]

In order to solve the above-mentioned first problem, according to the present invention, only a past important area is to be refreshed, and macroblocks included in the area are refreshed by a predetermined number. Intra coding is performed more than the number of times.

According to the present invention, it is possible to recover the image quality deterioration of the important area in a short time and not to leave the image quality deterioration of the part which was the important area in the past.

In order to solve the first problem,
In the image encoding device of the present invention, only the important region in the past is stored in the storage means, so that only that region is to be refreshed. If the number of times intra-coding of the block in the important area is performed by the counting means and the intra-coding control means, the intra-coding is performed if the number of times is equal to or less than a predetermined number.

According to the present invention, it is possible to recover the image quality deterioration of the important area in a short time and to prevent the image quality deterioration of the part which was the important area in the past from remaining.

In order to solve the second problem,
In the image coding method of the present invention, the order for determining the blocks to be included in the synchronization unit and the order for determining the blocks to be intra-coded are made different from each other and included in one synchronization unit. Minimize the number of refresh intra macroblocks.

According to the present invention, it is possible to minimize the number of macro blocks subjected to refresh intra coding due to transmission errors.

In order to solve the second problem,
The image coding apparatus according to the present invention is configured so that the order generating means for determining a block to be included in a synchronization unit and the order generating means for determining a macroblock to be intra-coded are different.

According to the present invention, it is possible to minimize the number of macro blocks subjected to refresh intra coding due to transmission errors.

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION
An image coding method in which an input digital video signal is divided into blocks, and the divided blocks are used as units of coding, and some blocks included in one picture are periodically intra-coded. Important regions in one or more pictures are stored in units of blocks, and control is performed such that blocks included in the regions are intra-coded a predetermined number of times or more.

Therefore, in the present invention, important regions in one or more past pictures are stored in units of blocks, and control is performed such that blocks included in the regions are intra-coded a predetermined number of times or more. Yes, only macroblocks included in an important area stored in block units are to be subjected to intra-coding, and macroblocks in the area are intra-coded at least a predetermined number of times.

The invention described in claim 2 of the present invention is characterized by claim 1
In the described image coding method, a block that is determined not to be included in an important region in a current picture and determined to be included in an important region in a past picture is important until a predetermined number of times or more is intra-coded. It is characterized in that control is performed so as to be stored as a special area.

Therefore, a block determined not to be included in an important area in the current picture and determined to be included in an important area in a past picture is regarded as an important area until intra-coded more than a predetermined number of times. The control is performed so that the macroblock in the important area can be intra-coded a predetermined number of times or more.

According to a third aspect of the present invention, there is provided an important area determining step of determining whether a block included in an input picture is included in an important area, and determining whether the block is included in an important area. By storing in block units, counting the number of times intra-coding of blocks included in the important region is performed, and allowing the blocks included in the important region to be intra-coded a predetermined number of times or more. , And intra coding control processing.

Therefore, the intra coding control processing can be realized by software.

According to a fourth aspect of the present invention, a block included in an input picture is stored in a block unit so that it can be determined whether or not the block is included in an important area. This is a computer-readable data recording medium that stores as an important area until a contained block is intra-coded a predetermined number of times or more.

Therefore, according to the present invention, it is possible to store software for performing the intra-encoding control processing.

According to a fifth aspect of the present invention, there is provided a dividing means for dividing an input digital image signal into blocks, and an intra determining unit for determining whether or not a current block among the blocks included in one picture is to be intra-coded. Encoding determination means, and the divided block as a unit, a block determined to be intra-coded, an image coding apparatus having an image coding means for intra-coding,
Important area determining means for determining whether the current block is included in an important area among blocks included in one picture, and important area storing means for storing important areas in one or more past pictures in block units And counting means for counting the number of times each block in the important area is intra-coded, and intra-coding control means for controlling each block in the important area to be intra-coded a predetermined number of times or more. An image encoding apparatus characterized in that:

Therefore, according to the present invention, the important area determining means determines whether or not the corresponding macroblock is important, and the result is stored in the storage means. If so, the macro block is regarded as a non-important area, and if the number of times is equal to or less than a predetermined number, intra coding is performed, and the corresponding macro block is continuously stored as an important area.

According to a sixth aspect of the present invention, there is provided a dividing means for dividing an input digital image signal into blocks, and an intra-frame for judging whether a current block among the blocks included in one picture is intra-coded. Encoding determining means; image encoding means for performing intra-coding on the blocks determined to be intra-coded in units of the divided blocks; and, among blocks included in one picture, the current block is important. Important region determining means for determining whether or not an important region is included in the important region, important region storing means for storing an important region in one or more past pictures in block units, and each block in the important region is intra-coded. Counting means for counting the number of times the data has been input, and an input means for controlling each block in the important area to be intra-coded at least a predetermined number of times. By the encoding control unit, an image decoding apparatus characterized in that it constitutes a coded data decoding means for decoding the encoded data.

Therefore, according to the present invention, it is possible to decode image-decoded data.

According to a seventh aspect of the present invention, there is provided a dividing means for dividing an input digital image signal into blocks, and an intra decision unit for judging whether or not a current block among the blocks included in one picture is intra-coded. Encoding determining means; image encoding means for performing intra-coding on the blocks determined to be intra-coded in units of the divided blocks; and, among blocks included in one picture, the current block is important. Important region determining means for determining whether or not an important region is included in the important region, important region storing means for storing an important region in one or more past pictures in block units, and each block in the important region is intra-coded. Counting means for counting the number of times the data has been input, and an input means for controlling each block in the important area to be intra-coded at least a predetermined number of times. By the encoding control unit, an image coding and decoding apparatus characterized in that it constitutes a coded data decoding means for decoding the encoded data.

According to an eighth aspect of the present invention, there is provided an important area determining means for determining whether a current block is included in an important area among blocks included in one picture,
Important area storage means for storing an important area in one or more past pictures in block units; counting means for counting the number of times each block in the important area has been intra-coded; This is a wireless image communication terminal device that performs an intra-encoding control process including a control unit that performs control so that intra-encoding is performed more times than the number of times.

According to a ninth aspect of the present invention, an input digital video signal is divided into blocks, and the divided blocks are used as units of encoding, and some blocks included in one picture are periodically divided. When a plurality of blocks are used as one synchronization unit and a synchronization word for recognizing the synchronization unit is added, intra coding is performed in an order different from the order for determining blocks to be included in the synchronization unit. This is an image encoding method characterized by determining a block to be encoded.

Therefore, according to the present invention, by determining the blocks to be intra-coded in an order different from the order for determining the blocks to be included in the synchronization unit, it is possible to determine the number of intra-frames included in one synchronization unit. It has the effect of minimizing the number of macro blocks.

The invention described in claim 10 of the present invention
9. The image coding method according to item 9, characterized in that control is performed such that blocks to be intra-coded within one picture are included in different synchronization units.

Therefore, according to the present invention, there is an effect of minimizing the number of intra macroblocks included in one synchronization unit.

According to an eleventh aspect of the present invention, an input digital video signal is divided into blocks, and the divided blocks are used as units of encoding, and some blocks included in one picture are periodically divided. Determining, in intra-coding, a plurality of blocks as one synchronization unit and adding a synchronization word for recognizing the synchronization unit, an order different from an order for determining blocks to be included in the synchronization unit; Performing an intra-encoding control process by performing intra-encoding of a block in a picture in accordance with the different order.

Therefore, according to the present invention, the processing for determining the block to be intra-coded in an order different from the order for determining the blocks to be included in the synchronization unit is realized by software.

According to a twelfth aspect of the present invention, an input digital video signal is divided into blocks, and the divided blocks are used as units of encoding, and a part of blocks included in one picture is periodically divided. Determining, in intra-coding, a plurality of blocks as one synchronization unit and adding a synchronization word for recognizing the synchronization unit, an order different from an order for determining blocks to be included in the synchronization unit; Intra-coding blocks in a picture according to the different order.

According to the present invention, it is possible to store software for performing processing for determining a block to be intra-coded in an order different from the order for determining blocks to be included in a synchronization unit.

According to a thirteenth aspect of the present invention, there is provided a dividing means for dividing an input digital image signal into blocks.
Of the blocks included in the picture, an intra-encoding determination unit that determines whether the current block is to be intra-encoded, and the block that is determined to be intra-encoded using the block as a unit of encoding, and intra-encodes the block that is determined to be intra-encoded Image encoding means, synchronizing unit generating means for integrating a plurality of blocks into one, and a synchronizing unit for adding a synchronizing word for recognizing the synchronizing unit, and a block to be included in the synchronizing unit An image coding apparatus comprising: an order generating unit that generates an order different from the order for determining the order; and an intra-coding control unit that controls to intra-code the block according to the order. .

According to the present invention, an order different from the order for determining the blocks to be included in the synchronization unit is generated, and the blocks are controlled to be intra-coded according to this order, so that the blocks are included in one synchronization unit. This has the effect of minimizing the number of intra macroblocks to be used.

According to a fourteenth aspect of the present invention, there is provided a dividing means for dividing an input digital image signal into blocks.
Of the blocks included in the picture, an intra-encoding determination unit that determines whether the current block is to be intra-encoded, and the block that is determined to be intra-encoded using the block as a unit of encoding, and intra-encodes the block that is determined to be intra-encoded Image encoding means, synchronizing unit generating means for integrating a plurality of blocks into one, and a synchronizing unit for adding a synchronizing word for recognizing the synchronizing unit, and a block to be included in the synchronizing unit Decoding means for decoding coded data by order generation means for generating an order different from the order for determining, and intra-coding control means for controlling to intra-code the blocks according to the order. An image decoding apparatus characterized by comprising:

Therefore, according to the present invention, encoded data can be decoded.

According to a fifteenth aspect of the present invention, there is provided a dividing means for dividing an input digital image signal into blocks.
Of the blocks included in the picture, an intra-encoding determination unit that determines whether the current block is to be intra-encoded, and the block that is determined to be intra-encoded using the block as a unit of encoding, and intra-encodes the block that is determined to be intra-encoded Image encoding means, synchronizing unit generating means for integrating a plurality of blocks into one, and a synchronizing unit for adding a synchronizing word for recognizing the synchronizing unit, and a block to be included in the synchronizing unit Order generating means for generating an order different from the order for determining, an intra-encoding control means for controlling to intra-encode a block according to the order, and data encoded by the intra-encoding control means. And a decoding means for decoding the image.

Therefore, according to the present invention, it can be said that the present invention is an image encoding / decoding device having both an image encoding device and an image decoding device.

According to a sixteenth aspect of the present invention, there is provided a dividing means for dividing an input digital image signal into blocks.
Of the blocks included in the picture, an intra-encoding determination unit that determines whether the current block is to be intra-encoded, and the block that is determined to be intra-encoded using the block as a unit of encoding, and intra-encodes the block that is determined to be intra-encoded Image encoding means, synchronizing unit generating means for integrating a plurality of blocks into one, and a synchronizing unit for adding a synchronizing word for recognizing the synchronizing unit, and a block to be included in the synchronizing unit And an image encoding apparatus having an order generation unit that generates an order different from the order for determining the order, and an intra-encoding control unit that controls to intra-encode the block according to the order. Wireless image communication terminal device.

Therefore, according to the present invention, in the wireless video communication terminal apparatus, an order different from the order for determining the blocks to be included in the synchronization unit is generated, and the blocks are intra-coded according to this order. As a result, intra coding control processing can be performed.

(Embodiment 1) An embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 shows the configuration of the embodiment of the present invention. First, each component will be described. In FIG. 1, 101
Denotes a raster / macroblock conversion, 102 denotes a motion detection unit, and 103 denotes a frame memory, in which a reproduced image of a previous picture is stored. 104 is a memory control unit, 105 is an important area determination unit, 106 is an important area memory, which stores the number of times each macroblock should be intra-coded, and 0 indicates a non-important area. 107 is I
NTER / INTRA control unit, 108 is a subtractor, 109 is a discrete cosine transform unit (DCT), 110 is a quantization unit,
111 is a variable length coding unit for DCT coefficients, 112 is inverse quantization, 113 is an inverse discrete cosine transform, 114 is an adder, 115 is a variable length coding unit for a motion vector, 1
Reference numeral 16 denotes a multiplexing unit for DCT coefficients and motion vectors.

Reference numeral 120 denotes macroblock data; 121, a difference value sum between the current macroblock and a macroblock located at the same position as the previous picture; 122, a motion vector; 123, whether or not the region is an important region; It is a value indicating the number of times of conversion. Next, the operation of each unit will be described in detail.

The input image is converted to a raster macroblock conversion unit.
In 101, 16 * 16 pixel size block (luminance signal)
And 8 * 8 pixel size blocks (color difference signals) and output. Next, the motion detector 102 compares the macroblock data 120 with the previous picture in the frame memory 103 and outputs a motion vector 122 of the current macroblock. Further, a sum 121 of difference values between the current macroblock data 120 and the macroblock at the same position in the previous picture is calculated.

Next, an important area determination result 123 indicating whether or not the current macroblock is an important area and the number of times intra coding should be performed is read from the important area memory 106. Here, if the current macroblock is not included in the important area, the INTER / INTRA determination unit 107 switches the switch to the frame memory side, and inputs the predicted image corrected by the motion vector to the subtractor. If the area is the important area, the switch is switched to the “0” side, a pixel value of zero is input to the subtractor, and the number of times the current macroblock in the important area memory is to be intra-coded is reduced by one. If this value becomes 0, this macroblock is regarded as an insignificant area and 0
Otherwise, the region is regarded as an important region, and is intra-coded the number of times indicated by the value.

The important area determination unit 105 compares the difference value 121 with a predetermined threshold value.
The current macroblock is determined as an important area. If it is determined that the area is an important area, the contents of the current macro block in the important area memory 106 are updated. Assuming that the number of times a macroblock included in the important area should be intra-coded is three, the content of the current macroblock in the important area memory 106 is three.

In the subtractor 108, the current macro block 120
And predicted image (zero if determined to be intra-coded)
Is calculated. The discrete cosine transform unit 109 converts the DCT coefficients into DCT coefficients, and the quantization unit 110 quantizes them. The quantized coefficients are encoded by the variable-length encoding unit 111 into a variable-length code. Further, the quantized coefficient is inversely quantized by the inverse quantization unit 112 to be a DCT coefficient, and is obtained by the inverse discrete cosine transform unit 113 to be a difference value. The adder 114 reproduces the image of the current picture by adding the difference value to the predicted image (zero when the intra-coding is determined), and stores the image in the frame memory 103. The motion vector 122 is variable-length coded by the variable-length coding unit 115, multiplexed by the multiplexing unit 116 together with the variable-length code of the DCT coefficient, and output.

The updating of the important area memory 106 will be described in more detail with reference to FIG. In FIG. 2, the upper diagram shows the contents of the important area memory in each picture. The middle diagram corresponds to each picture in the upper stage, and shows an area determined to be important. Similarly, the lower diagram also corresponds to each picture in the upper stage, and shows the contents of the important area memory updated after the important area determination.

The contents of the important area memory indicate, for each macroblock, whether or not the macroblock is included in the important area. It is indicated by a numerical value, where 0 indicates an insignificant area and anything other than 0 indicates an important area. A non-zero value indicates how many times the macroblock should be intra-coded. As described above, the flag indicating whether the area is important / insignificant and the number of times intra-coding is to be performed are represented by one memory.

A description will be given step by step with reference to FIG. The number of macroblocks intra-coded into one picture is 2
Assume that

Since the contents of the important area memory have not been updated yet (b), there is no macroblock to be intra-coded. In the first picture, it is assumed that the important area is determined as shown in FIG. After that, the important area of the first picture is reflected in the important area memory (c). Assuming that a macroblock included in an important region is intra-coded three times, a value of 3 is written in that region.

In the second picture, two macroblocks are intra-coded (shaded macroblocks) according to the content (d) of the important area memory, and the value of the macroblock in the important area memory is reduced by one. The value in the memory corresponding to the intra-coded macroblock is 2, this macroblock is stored as an important area, and is intra-coded twice thereafter.

Next, the important area in the second picture is (d)
Assume that it is determined as follows. The important area of the second picture is reflected in the important area memory (f). This is the third, fourth, fifth
... and continue.

As described above, the contents of the important area memory are updated for each picture, and macro blocks in the area are sequentially intra-coded.

In the above description, the important area is determined using the sum of the difference values between the current macroblock and the macroblock at the same position in the previous picture. However, the present invention limits the method of determining the important area. Not something.

Although the order of intra-coding macroblocks in the important area is set to be continuous in the horizontal direction, the present invention does not limit the order of intra-coding.

It can be easily analogized that the number of intra-coded pictures and the number of intra-coded macroblocks included in the important area can be arbitrarily set.

The present invention can also be realized by software, and the present invention can be realized by reading from a recording medium containing the software. In addition, a decoder that can decode data encoded according to the present invention can provide an easy-to-view image in which recovery of image quality in an important area is quick even when image quality is deteriorated due to an error that occurs during transmission. is there.

If a codec having both an encoder and a decoder according to the present invention is used on both the transmitting side and the receiving side, real-time bidirectional image communication can be performed.

The present invention is effective in wireless transmission in which an error is likely to occur during transmission, and is particularly effective in a wireless image communication terminal device as shown in FIG. 12, reference numeral 1201 denotes a receiving unit, 1202 denotes a camera unit,
1203 is a monitor unit, 1204 is a speaker, 1205 is a control unit, 1206
Is the mouthpiece. The image captured by the camera unit 1202 is
The image is encoded by the internal image encoding device. Mouthpiece 1206
The voice of the sender is captured, encoded, multiplexed with the video signal, and transmitted. It also receives radio signals from the game.
Received at 1201, the video signal and the audio signal are separated. The video signal is decoded by the internal image decoding device,
Displayed in 1203. The audio signal from the game is similarly decoded and output from the speaker 1204.

Although the present embodiment is a wireless portable terminal, it can also be realized by a form in which a wireless transmitting / receiving device is connected to a computer.

(Embodiment 2) Hereinafter, an embodiment of the present invention will be described with reference to FIGS.

FIG. 3 shows the configuration of the embodiment of the present invention. First, each component will be described. 3, the same components as those shown in FIG. 1 are denoted by the same reference numerals and description thereof will be omitted.

In FIG. 3, reference numeral 301 denotes an INTER / INTRA control unit,
Reference numeral 302 denotes a synchronization word generator. 310 is the macroblock number of the current macroblock, 311 is the number of macroblocks to be intra-coded into one picture (this is M), and 312 is the number of macroblocks contained in one picture ( This is N).

Next, the operation of each unit will be described in detail.

The raster / macro block converter 101 divides the input image into macro blocks and outputs the number 310 of the current macro block. The macroblock number is 1 in the upper left macroblock, and increases in the horizontal direction to 2.3.4. After reaching the right end, counting is continued from the left end one step below (FIG. 4).

The INTER / INTRA determination unit 301 determines that the current macroblock is INTRA based on the macroblock number 310 and the values of N and M.
Determine if it should be encoded. M is 5, N is 9
Assume 9.

The five intra-coded macroblock numbers (M1, M2, M3, M4, M5) are determined. First, the initial values of M1 to M5 are determined. Since GOB uses eleven horizontally continuous macro blocks as one synchronization unit, five intra-coded macro blocks are determined in a different order.

In order for macroblocks to be intra-coded to be included in different synchronization units, macroblocks at positions spaced as long as possible in the horizontal direction are intra-coded. That is, the initial values of the numbers to be intra-coded are as follows.

M1 = 1 M2 = N / M * 1 = 99/5 * 1 = 19 M3 = N / M * 2 = 99/5 * 2 = 39 M4 = N / M * 3 = 99/5 * 3 = 59 M5 = N / M * 4 = 99/5 * 4 = 79 With this value as the initial value, it is incremented by one for each picture, and is set to 1 when the value of N is exceeded. The order of macroblocks to be intra-coded is as shown in FIG.

When the input macroblock number 310 is M1-M
If any one of 5 is equal, intra coding is performed, and the switch is switched to “0” side. If they are not equal to each other, normal INTER encoding shall be used,
Switch the switch to the predicted image output side.

Synchronization word generation section 302 outputs a synchronization word and header information relating to the corresponding synchronization unit for every 11 macroblocks, and multiplexing section 116 performs variable length coded DCT.
It is multiplexed with coefficients and motion vector information and output.

Note that, in this method, macroblocks to be intra-coded in the order shown in Equation 1 are determined. However, even if the macroblocks are determined using the order shown in FIG. 6 and the method shown in FIG. Macroblocks to be intra-coded can be arranged in different synchronization units.

The present invention can also be realized by software, and the present invention can also be realized by reading from a recording medium containing the software. In addition, a decoder that can decode data encoded according to the present invention can reduce the number of missing intra-coded macroblocks even when image quality is deteriorated due to an error that occurs during transmission, It is possible to provide an easy-to-view image.

Further, if a codec having both an encoder and a decoder according to the present invention is used on both the transmitting side and the receiving side, real-time two-way image communication can be performed. Further, the present invention is effective in wireless transmission in which an error is likely to occur during transmission, and is particularly effective in a wireless image communication terminal device as shown in FIG. Further, the present embodiment is a wireless portable terminal, but it can also be realized in a form in which a wireless transmitting / receiving device is connected to a computer.

[0092]

As described above, according to the present invention, it is possible to recover image quality deterioration of an important portion in a picture in a short time, and to maintain image quality deterioration of a portion which was an important region in the past. Is also gone. Therefore, even if image transmission is performed using a transmission path in which a transmission error occurs, it is possible to provide an image that is easy to see.

According to the present invention, intra-coded macroblocks are arranged and transmitted in different synchronization units. Therefore, even if a transmitted synchronization unit is lost due to a transmission error, not all intra macroblocks are lost, so that a portion where the image quality is deteriorated is quickly recovered, and it is possible to provide an easy-to-view image.

[Brief description of the drawings]

FIG. 1 is a diagram showing the configuration of an embodiment of the first invention.

FIG. 2 is a diagram showing a state in which an important area memory is updated.

FIG. 3 is a diagram showing a configuration of an embodiment of the second invention.

FIG. 4 is a diagram showing the order of macroblock numbers.

FIG. 5 is a diagram showing an example of an arrangement of macro blocks to be intra-coded according to the present invention;

FIG. 6 shows the order of macroblock numbers for determining a macroblock to be intra-coded.

FIG. 7 is a diagram showing another example of the arrangement of macro blocks to be intra-coded in the present invention.

FIG. 8 shows an arrangement of intra macro blocks in a conventional cyclic refresh method.

FIG. 9 is a configuration diagram of a GOB.

FIG. 10 is a diagram showing a problem when a conventional important region is intra-coded.

FIG. 11 is a diagram showing positions of intra-coded macroblocks included in GOB.

FIG. 12 illustrates an example of a wireless image communication terminal.

[Explanation of symbols]

101 Raster / macro block converter 102 Motion detector 103 Frame memory 104 Memory controller 105 Important area decision unit 106 Important area memory 107 INTER / INTRA decision unit 108 Subtractor 109 Discrete cosine transform unit 110 Quantization unit 111 Variable length coding Section 112 inverse quantization section 113 inverse discrete cosine transform section 114 adder 115 variable length coding section 116 multiplexing section 120 macroblock data 121 difference value sum 122 motion vector 123 important area judgment result 301 INTER / INTRA judgment section 302 sync word Generation unit 310 Macroblock number 311 Number of macroblocks to be intra-coded in one picture 312 Number of macroblocks in one picture 1201 Receiving unit 1202 Camera unit 1203 Monitor unit 1204 Speaker 1205 Control unit 1206 Mouthpiece

Claims (16)

[Claims] 1. An input digital video signal is divided into blocks, and the divided blocks are used as units for encoding.
An image coding method for periodically intra-coding a part of blocks included in one picture, wherein an important area in one or more past pictures is stored in units of blocks, and the blocks included in the area are stored. An image coding method, wherein control is performed such that intra-coding is performed a predetermined number of times or more. 2. A block determined not to be included in an important area in a current picture and determined to be included in an important area in a past picture is regarded as an important area until intra-coded at least a predetermined number of times. 2. The image encoding method according to claim 1, wherein control is performed to store the image. 3. An important area determining step of determining whether a block included in an input picture is included in an important area, a step of storing whether or not the block is included in the important area in block units, Performing an intra-encoding control process by counting the number of times intra-encoding of a block included in the region and allowing the block included in the important region to be intra-encoded a predetermined number of times or more An intra-coding control method characterized by the above-mentioned. 4. A block included in an input picture is stored in a block unit so that it can be determined whether or not the block is included in an important area. A computer-readable data recording medium that stores information as an important area until it is converted into a computer. 5. A dividing means for dividing an input digital image signal into blocks, an intra-encoding judging means for judging whether or not the current block among the blocks included in one picture is intra-encoded, In an image coding apparatus having an image coding unit for performing intra coding, a block determined to be intra-coded is used as a unit for each block, and among the blocks included in one picture, the current block is included in an important area. Important area determination means for determining whether or not the important area is included; important area storage means for storing important areas in one or more past pictures in block units; and number of times each block in the important area has been intra-coded. A counting means for counting, and an in-control means for controlling each block in the important area to be intra-coded a predetermined number of times or more. Image encoding apparatus comprising: the La encoding control means. 6. A dividing means for dividing an input digital image signal into blocks, an intra-encoding judging means for judging whether a current block among the blocks included in one picture is to be intra-encoded, and Image encoding means for intra-encoding a block determined to be intra-encoded on a block-by-block basis, and determining whether the current block is included in an important area among blocks included in one picture. Important area determining means for determining, important area storing means for storing an important area in one or more past pictures in block units, and counting means for counting the number of times each block in the important area is intra-coded, By intra-coding control means for controlling each block in the important area to be intra-coded more than a predetermined number of times Image decoding apparatus characterized in that it constitutes a coded data decoding means for decoding the encoded data. 7. A division unit that divides an input digital image signal into blocks, an intra-encoding determination unit that determines whether or not a current block among the blocks included in one picture is intra-encoded, Image encoding means for intra-encoding a block determined to be intra-encoded on a block-by-block basis, and determining whether the current block is included in an important area among blocks included in one picture. Important area determination means for determining, important area storage means for storing an important area in one or more past pictures in block units, and counting means for counting the number of times each block in the important area has been intra-coded, By intra-coding control means for controlling each block in the important area to be intra-coded more than a predetermined number of times Picture coding and decoding apparatus characterized in that it constitutes a coded data decoding means for decoding the encoded data. 8. A block included in one picture,
Important area determining means for determining whether or not the current block is included in the important area; important area storing means for storing an important area in one or more past pictures in units of blocks; Wireless image communication for performing an intra-encoding control process, comprising: a counting unit that counts the number of times of intra-encoding, and a control unit that controls each block in the important area to be intra-encoded a predetermined number of times or more. Terminal device. 9. An input digital video signal is divided into blocks, and the divided blocks are used as units for encoding.
In the case where some blocks included in one picture are periodically intra-coded and a plurality of blocks are used as one synchronization unit and a synchronization word for recognizing the synchronization unit is added, a block to be included in the synchronization unit is determined. An image coding method characterized in that blocks to be intra-coded are determined in an order different from the order for the image coding. 10. The image coding method according to claim 9, wherein control is performed such that blocks to be intra-coded within one picture are included in different synchronization units. 11. An input digital video signal is divided into blocks, a part of a block included in one picture is periodically intra-coded using the divided blocks as a unit of coding, and a plurality of blocks are divided into one block. When adding a synchronization word for recognizing the synchronization unit as one synchronization unit, determining an order different from the order for determining blocks to be included in the synchronization unit; and Performing an intra-encoding control process by performing an intra-encoding step on an intra-frame. 12. An input digital video signal is divided into blocks, a part of a block included in one picture is periodically intra-coded using the divided block as a unit of coding, and a plurality of blocks are divided into one block. When adding a synchronization word for recognizing the synchronization unit as one synchronization unit, determining an order different from the order for determining blocks to be included in the synchronization unit; and And a computer-readable data recording medium containing an intra-encoding control process. 13. A dividing means for dividing an input digital image signal into blocks; an intra-encoding judging means for judging whether or not the current block among the blocks included in one picture is intra-encoded; An image encoding unit that intra-encodes a block determined to be intra-encoded as a unit of encoding, a synchronization unit generation unit that integrates a plurality of blocks into one as a synchronization unit, and recognizes the synchronization unit. Synchronizing word addition generating means for adding a synchronizing word for the same, order generating means for generating an order different from the order for determining the blocks to be included in the synchronizing unit, and controlling to intra-encode the blocks according to the order An image encoding device comprising: an intra encoding control unit. 14. A dividing means for dividing an input digital image signal into blocks; an intra-coding judging means for judging whether or not the current block among the blocks included in one picture is intra-coded; An image encoding unit that intra-encodes a block determined to be intra-encoded as a unit of encoding, a synchronization unit generation unit that integrates a plurality of blocks into one as a synchronization unit, and recognizes the synchronization unit. Synchronizing word addition generating means for adding a synchronizing word for the same, order generating means for generating an order different from the order for determining the blocks to be included in the synchronizing unit, and controlling to intra-encode the blocks according to the order A decoding means for decoding the coded data by the intra coding control means. Decoding device. 15. A dividing means for dividing an input digital image signal into blocks, an intra-encoding judging means for judging whether or not the current block is intra-encoded among the blocks included in one picture; An image encoding unit that intra-encodes a block determined to be intra-encoded as a unit of encoding, a synchronization unit generation unit that integrates a plurality of blocks into one as a synchronization unit, and recognizes the synchronization unit. Synchronizing word addition generating means for adding a synchronizing word for the same, order generating means for generating an order different from the order for determining the blocks to be included in the synchronizing unit, and controlling to intra-encode the blocks according to the order Intra-encoding control means, and decoding means for decoding data encoded by the intra-encoding control means Picture coding and decoding apparatus according to claim and. 16. A dividing means for dividing an input digital image signal into blocks, an intra-encoding judging means for judging whether or not the current block among the blocks included in one picture is to be intra-encoded; An image encoding unit that intra-encodes a block determined to be intra-encoded as a unit of encoding, a synchronization unit generation unit that integrates a plurality of blocks into one as a synchronization unit, and recognizes the synchronization unit. Synchronizing word addition generating means for adding a synchronizing word for the same, order generating means for generating an order different from the order for determining the blocks to be included in the synchronizing unit, and controlling to intra-encode the blocks according to the order A wireless image communication terminal device, comprising: an image encoding device having intra-coding control means.