JPH06319124A - Picture data converter and its inverter - Google Patents

Abstract

PURPOSE:To provide advantages of both the inter-frame prediction coding system and the in-frame coding system by giving block uncoded data as to a block whose content is the same as that of a preceding frame and giving data subject to in-frame coding as to a block whose content differs from that of the preceding frame to a picture data inverter. CONSTITUTION:Picture data subject to A/D-conversion are given to a subtractor 41 of a picture data converter 40 in the unit of blocks. The subtractor 41 obtains difference data between received picture data and picture data of a same picture element of one preceding frame and provides the difference data to a discrimination circuit 43. Block uncoding data representing a block whose content is the same as that of a preceding frame are given to a multiplexer 44 based on the discrimination and data subject to in-frame coding as to a block whose content differs from that of the preceding frame are given to the multiplexer 44. Thus, when the data are outputted to a transmission line, the quantity of data given to the picture data inverter is less and the efficiency is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image data conversion device for converting input image data to record it on a recording medium or output it on a transmission line, and its inverse conversion device.

[0002]

2. Description of the Related Art For example, in a game system using a computer, as is well known, game software is recorded on a recording medium (for example, a CD-ROM) and provided to a user. Various types of data such as image data, audio data, and text data are recorded on such a recording medium. However, when recording natural image (moving image) data, they are compressed and encoded for recording.

Conventionally, the interframe predictive coding method shown in FIG. 4 and the intraframe coding method shown in FIG. 6 have been applied as a method of coding such natural image data.

First, an encoder (encoder) according to the interframe predictive coding system will be described. The analog / digital converted image data is input to the inter-frame predictive encoder 10 in block units obtained by dividing one image vertically and horizontally. The difference (prediction error) between the input image data and the image data of the same pixel one frame before is subtracted by the subtracter 1.
Taken by 1. The difference data is subjected to a discrete cosine transform, which is one type of orthogonal transform method, by the discrete cosine transformer 12, is given to the quantizer 13, and is quantized, and is further variable length encoded by the variable length encoder 14. Is output. The quantized signal output from the quantizer 13 is also supplied to the inverse quantizer 15 and inversely quantized and then supplied to the inverse discrete cosine transformer 16, and the inverse discrete cosine transformer 16 performs the inverse discrete cosine transform. It is converted to the locally reproduced difference data and given to the adder 17. The image data of one frame before is given to the adder 17, and the difference data of the local reproduction is added to the image data of the previous frame to obtain the image data of the local reproduction and give it to the frame memory 18. The frame memory 18 is
It is provided as a 1-frame delay circuit,
The subtractor 11 described above using the image data of one frame before
And the image data of one frame before is supplied to the adder 17.

An interframe predictive decoder (decoder) 20 provided in the game software reproducing apparatus and corresponding to the interframe predictive encoder (encoder) 10 shown in FIG. 4 has a structure shown in FIG.

The input coded image data is supplied to the variable length decoder 21. The variable length decoder 21 performs the reverse processing of the variable length encoder 14 described above and supplies the converted image data to the inverse quantizer 22. The inverse quantizer 22 and the inverse discrete cosine transformer 23 are the quantizer 13 and the discrete cosine transformer 1 provided in the encoder 10 described above.
The reverse processing of 2 is performed to convert the data into interframe difference data. The inter-frame difference data is added with the image data of one frame before in the adder 24 to be reproduced image data. The reproduced image data obtained in this way is
It is output to the display unit and is given to the frame memory 25 that operates as a one-frame delay circuit. The frame memory 25 supplies the image data of one frame before to the adder 24 described above.

Next, an encoder (encoder) according to the intra-frame coding method used as another coding method of the game system will be described with reference to FIG.

The image data that has been subjected to analog / digital conversion is input to the intra-frame encoder 30 in block units in which one image is divided vertically and horizontally. The input image data is given to the discrete cosine transformer 31, the discrete cosine transform is performed by the discrete cosine transformer 31, and the quantizer 32 is given. The quantizer 32 quantizes the image data subjected to the discrete cosine transform and supplies it to the variable length encoder 33, and the variable length encoder 33 variable length encodes the input image data and outputs it.

An intra-frame encoder (encoder) 3 shown in FIG. 6 provided in the game software reproducing apparatus.
The intraframe decoder (decoder) 35 corresponding to 0 is
It has the configuration shown in FIG.

The input encoded image data is given to the variable length decoder 36. The variable length decoder 36 performs the inverse process of the variable length encoder 33 described above and supplies the converted image data to the inverse quantizer 37. The inverse quantizer 37 and the inverse discrete cosine transformer 38 are the quantizer 32 and the discrete cosine transformer 3 provided in the encoder 30 described above.
The reverse processing of 1 is performed to reproduce the image data. The reproduced image data thus obtained is output to the display unit.

[0011]

The inter-frame predictive coding system generally has high compression efficiency, but it requires a large amount of memory, and the circuit is complicated and large-scaled.
In the case of a game system, since the manufacturer creates the recording medium recording the game software, the problem that the creating device having the encoder is complicated, the scale becomes large, and a large amount of expensive memory is required, It's not a big problem. However, since the reproducing apparatus for the recording medium is provided to the user, such a problem is a serious problem because it causes an expensive device as a result.

In the case of the interframe predictive coding system,
The differential data between successive frames is subjected to discrete cosine transform, the encoder is provided with an inverse discrete cosine transformer for local reproduction, and the decoder is provided with an inverse discrete cosine transformer. In the case of a game system, the encoder and decoder are
There is a possibility that the calculation precisions of the two inverse discrete cosine transformers are different. If the calculation accuracy is different, the image quality is deteriorated due to the accumulation of calculation errors.

On the other hand, the intraframe coding method has an advantage that it uses less memory, but has a drawback that coding efficiency is poor. Therefore, a method of coping with lowering the frame rate has been proposed, but even with this, the coding efficiency is poor in the case of a fine pattern, and since the frame rate is lowered, an unnatural display image may result depending on the motion content. The drawback occurs.

The present invention has been made in consideration of the above points, and provides an image data conversion device and its inverse conversion device which have the advantages of both the inter-frame predictive coding system and the intra-frame coding system. Is what you are trying to do.

[0015]

In order to solve such a problem, the image data conversion apparatus of the first aspect of the present invention stores the image data of the frame to be processed and the image data of one frame before.
One image is divided into a plurality of blocks at the same position, and a determination unit determines whether or not the image data of successive frames has the same content, and the determination unit has different image content. It is determined that the intra-frame encoding means for performing intra-frame encoding on the image data of the block of the processing target frame, the intra-frame encoded data encoded by the intra-frame encoding means, and the determination means have the same content. And a data synthesizing unit for synthesizing the block uncoded data indicating that the processing target block has the same content as the previous frame, which is output when the determination is made, to form output image data.

The image data inverse conversion device of the second aspect of the invention separates the image data output by the image data conversion device of the first aspect of the invention into intra-frame coded data and block uncoded data. Data separating means, intra-frame decoding means for decoding intra-frame encoded data, and data separated by the data separating means for maintaining recorded contents when the data separated by the data separating means is block uncoded data Is an intra-frame coded data, an image memory for updating the stored contents to the image data output by the intra-frame decoding means.

[0017]

In the first aspect of the present invention, the determination means compares the image data of the frame to be processed and the image data of the previous frame for each block at the same position where one image is divided into a plurality of blocks, and compares them. It is determined for each block whether or not the image data of the frame has the same content. The intra-frame encoding means performs intra-frame encoding on the image data of the block of the processing target frame, which the determination means determines to have different image contents. The data synthesizing unit is a block indicating that the intra-frame coded data encoded by the intra-frame encoding unit and the processing target block output when the determining unit determines that the same content is the same as the previous frame. The uncoded data is combined to form output image data.

That is, in the first aspect of the present invention, for a block having the same content as the previous frame, block uncoded data to that effect is given to the image data inverse conversion device, and for a block having a content different from the previous frame, The intra-frame coded data is supplied to the image data inverse conversion device.

The image data inverse conversion device of the second invention is
The present invention relates to the image data conversion device of the first aspect of the present invention. The data separation means separates the image data output by the image data conversion device of the first aspect of the invention into intra-frame coded data and block uncoded data. The intraframe decoding means decodes the intraframe coded data and gives it to the image memory. The image memory maintains the recorded content when the data separated by the data separating means is block uncoded data, and is output by the intraframe decoding means when the data separated by the data separating means is intraframe encoded data. The stored contents are updated to the selected image data.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described in detail below in the order of an image data conversion device and its inverse conversion device with reference to the drawings.

FIG. 1 shows an image data conversion apparatus (encoder) according to the first embodiment. In FIG. 1, the analog / digital converted image data is converted into image data converter 4 in units of blocks obtained by dividing one image vertically and horizontally.
Input to 0. The input image data is subtracted from the subtracter 41.
And the switch circuit 42.

The subtractor 41 outputs the input image data and 1
Difference data from the image data of the same pixel before the frame is obtained and given to the determination circuit 43. The determination circuit 43 obtains the sum of squares of the difference data for each pixel in the current block, and compares the sum of squares with a predetermined threshold value. Here, the threshold value determines whether or not blocks at the same position between consecutive frames have the same content, that is,
It is selected so that it can be distinguished whether or not the image content is changed between successive frames. For example, if it is a still image, it is naturally judged that the contents are the same. Further, even in the case of a moving image, the blocks in the background portion are determined to have the same content. When the determination circuit 43 determines that the contents are the same, the determination circuit 43 gives an opening instruction signal to the switch circuit 42 and a switch circuit 45 described later, and blocks the block unencoded to the effect that intra-frame encoding has not been executed for the multiplexer 44. Give data. On the other hand, when it is determined that the contents are not the same, a closing instruction signal is given to the switch circuit 42 and the switch circuit 45 described later.

The input image data that has passed through the switch circuit 42 is applied to the discrete cosine converter 46. The input image data is subjected to discrete cosine transform by the discrete cosine transformer 46 and given to the quantizer 47. The quantizer 47 quantizes the image data subjected to the discrete cosine transform and supplies it to the variable length encoder 48, and the variable length encoder 48 variable length codes the inputted image data and outputs it to the multiplexer 44.

As described above, for the block having the same content as the previous frame, the block uncoded data to that effect is given to the multiplexer 44, and the block having the content different from the previous frame is intra-frame coded. The data is given to the multiplexer 44, and the multiplexer 44 multiplexes these and outputs them.

The quantized data output from the quantizer 47 is also supplied to the inverse quantizer 49, inversely quantized and supplied to the inverse discrete cosine transformer 50, which inverts the inverse discrete cosine transformer 50. Discrete cosine transform is performed and the image data is locally reproduced. Such locally reproduced image data is supplied to the frame memory 51 as a one-frame delay circuit via the switch circuit 45 so that the subtractor 41 can use it for calculating the difference between the target frame and the previous frame. . The frame memory 51 supplies the image data of one frame before to the subtractor 41 described above.

FIG. 2 shows the image data converter 4 shown in FIG.
1 shows a configuration of an image data inverse conversion device (decoder) 55 corresponding to 0 according to the first embodiment.

The input conversion data is given to the demultiplexer 56. The demultiplexer 56 separates the input data into block uncoded data and intra-frame coded data, gives an open instruction signal to the switch circuit 57 when block uncoded data is given, and on the other hand, When the intra-frame coded data is given, the closing instruction signal is given to the switch circuit 57, and the intra-frame coded data is given to the variable length decoder 58 through the switch circuit 57.

The variable length decoder 58 performs the reverse processing of the variable length encoder 48 described above and supplies the converted image data to the inverse quantizer 59. The inverse quantizer 59 and the inverse discrete cosine transformer 60 perform the inverse processing of the quantizer 47 and the discrete cosine transformer 46 provided in the above-mentioned encoder 40 to reproduce the image data. The reproduced image data obtained in this manner is given to the frame memory 61 which is a part of the display control configuration.

Thus, the frame memory 61 maintains the contents of the previous frame for the block to which the block uncoded data is given, and the contents to the reproduced image data for the block to which the intraframe coded data is given. To update.

Therefore, according to the first embodiment described above, the intraframe coding method is applied only to the image data of the block having the content different from that of the previous frame, and the data indicating that is applied to the block having the same content as the previous frame. Since the encoder and the decoder transmit and receive, the following effects can be obtained.

(1) The coding efficiency is improved as compared with the case where the intraframe coding method is simply applied. That is, with respect to the block having the same content as the previous frame, since the data to that effect is transmitted and received by the encoder and the decoder, the total amount of data transmitted and received is smaller than in the case where the intra-frame encoding method is simply applied.

(2) Since the interframe predictive coding method is not applied, the structure is simple and the memory used is small. Particularly, the effect is great on the decoder 55 side. As described above, in the case of the game system, since the decoder is provided to the user,
The significance of this effect is great.

(3) For a block having the same content as the previous frame, since data to that effect is only transmitted and received by the encoder and the decoder, such a block is not subjected to the inverse discrete cosine transform by the encoder and the decoder and is encoded. Since the blocks to be processed are also intraframe-coded, even if the calculation precisions of the inverse discrete cosine converters of the encoder and the decoder are different, the calculation error is not accumulated.

FIG. 3 shows the arrangement of an image data conversion apparatus according to the second embodiment of the present invention.

In FIG. 3, the analog-to-digital converted image data is input to the image data conversion device 70 in block units obtained by vertically and horizontally dividing one image. The input image data is given to the subtractor 71, the switch circuit 72, and the frame memory 73.

The frame memory 73 is provided as a one-frame delay circuit, and supplies the image data delayed by one frame, that is, the image data of the frame before the target frame to the subtractor 71. The subtractor 71 obtains difference data between the input image data and the image data of the same pixel one frame before and gives it to the determination circuit 74. Judgment circuit 7
4 is the sum of squares of the difference data for each pixel in the current block, compares the sum of squares with a predetermined threshold value, and blocks in the same position between consecutive frames are the same. Whether it is a block of content, ie
It is determined whether or not the image content has changed between successive frames. When the decision circuit 74 determines that the contents are the same, it gives the switch circuit 72 an open instruction signal and also gives the multiplexer 75 block-uncoded data indicating that intraframe coding is not being executed. On the other hand, if it is determined that the contents are not the same, a closing instruction signal is given to the switch circuit 72.

The input image data that has passed through the switch circuit 72 is applied to the discrete cosine converter 76. This image data is subjected to discrete cosine transform by the discrete cosine transformer 76 and given to the quantizer 77. The quantizer 77 quantizes the image data subjected to the discrete cosine transform, and supplies the quantized image data to the variable length encoder 78. Variable length encoder 7
8 variable-length-codes the quantized image data and outputs it to the multiplexer 75.

As described above, with respect to the block having the same content as the previous frame, the block uncoded data to that effect is given to the multiplexer 75, and the block having the content different from the previous frame is intra-frame encoded. The data is given to the multiplexer 75, and the multiplexer 75 multiplexes these and outputs them.

Since the configuration of the inverse converter of the image data in the second embodiment is the same as that of the first embodiment, its explanation is omitted.

Therefore, also in the second embodiment, the same effect as in the above-mentioned first embodiment can be obtained. here,
In the case of the second embodiment, since the encoder is not provided with the inverse quantizer and the inverse discrete cosine converter, the encoder configuration including the number of memories can be further simplified. Further, since the block to be coded is also intra-frame coded, it is possible to ignore the accumulated error that has conventionally occurred due to the difference in calculation accuracy between the inverse discrete cosine converter of the encoder and the decoder in inter-frame predictive coding. it can.

The present invention is not only applied to recording on a recording medium and reproducing from the recording medium, but
It can also be applied when a transmission system is used. Therefore, the application system is not limited to the game system.

[0042]

As described above, according to the present invention, the intra-frame coding method is applied only to the image data of the block having the content different from that of the previous frame, and the data indicating that is applied to the block having the same content as the previous frame. Are transmitted and received by the encoder and the decoder, so that it is possible to realize an image data conversion device and its inverse conversion device which have the advantages of both the inter-frame predictive coding system and the intra-frame coding system.

[Brief description of drawings]

FIG. 1 is a block diagram showing an image data conversion device of a first embodiment.

FIG. 2 is a block diagram showing an image data inverse conversion device according to a first embodiment.

FIG. 3 is a block diagram showing an image data conversion device of a second embodiment.

FIG. 4 is a block diagram showing a conventional interframe predictive encoder.

FIG. 5 is a block diagram showing a conventional interframe predictive decoder.

FIG. 6 is a block diagram showing a conventional intraframe encoder.

FIG. 7 is a block diagram showing a conventional intraframe decoder.

[Explanation of symbols]

40 ... Image data conversion device, 41 ... Subtractor, 42, 45
... switch circuit, 43 ... multiplexer, 46 ... discrete cosine transformer, 47 ... quantizer, 48 ... variable length encoder, 49, 59 ... inverse quantizer, 50, 60 ... inverse discrete cosine transformer, 51, 61 ... Frame memory, 55 ... Image data reverse conversion device.

Claims (2)

[Claims] 1. The image data of a frame to be processed and the image data of one frame before are compared for each block at the same position obtained by dividing one image into a plurality of images, and the image data of the succeeding frames have the same contents. Determination means for determining whether or not each block is different, and intra-frame encoding means for performing intra-frame encoding on the image data of the block of the processing target frame, which is determined by the determination means to have different image contents, In-frame coded data coded by the intra-frame coding means and block uncoded data indicating that the block to be processed has the same content as the previous frame, which is output when the above-mentioned judging means judges the same content. And a data synthesizing unit for synthesizing the image data to form output image data. 2. A data separation means for separating the image data output by the image data conversion apparatus according to claim 1 into intra-frame coded data and block uncoded data, and decoding the intra-frame coded data. When the data separated by the data separating means is block uncoded data, the recorded content is maintained, and when the data separated by the data separating means is intraframe coded data, An image data inverse conversion device, comprising: an image memory for updating the stored contents of the image data output by the intraframe decoding means.