JP2000333203A - Compression coding method, compression decoding method, compression coder and compression decoder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a compression coding method by which deterioration in color difference signals of image coding data can be reduced in the case of revising a component format to apply compression coding to the data and to provide a compression decoding method, a compression coder and a compression decoder. SOLUTION: In the case of using an MPEG coder to encode a 4:1:1 image signal, each pixel of color difference signals in the 4:1:1 image signals the pixel number of which is divisible by 4 and which is in existence on line numbers with a residue of 2 or 3 when being divided by 4 is replaced with each pixel whose position has no color difference signal on a line number that is divisible by 4 or has a residue of 1 when being divided by 4. In the case of encoding the image signal whose pixels are replaced as above by the MPEG coder, the coded signal is extracted as a 4:2:0 coded signal. A decoder side replaces pixels in a reverse way to the pixel replacement as above and can decode the signal into the original 4:1:1 signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compression encoding method, a compression decoding method, a compression encoding device, and a compression decoding device. The present invention relates to a compression encoding method, a compression decoding method, a compression encoding device, and a compression decoding device capable of compressing and decoding this.

[0002]

2. Description of the Related Art Each sampling frequency of two kinds of color difference signals is
A digital moving image signal of a 4: 2: 2 component coding system (hereinafter, referred to as １ ／ of that of the luminance signal)
4: 2: 2 image signal), the sampling frequency of each of the two types of color difference signals is の of that of the luminance signal, but a 4: 2: 0 component that transmits the color difference signals line-sequentially. Digital video signals of the encoding system (hereinafter, 4:
Image compression without complicating bus line control when the specifications are converted to a 2: 0 image signal) and the 4: 2: 0 image signal and additional information necessary for compression encoding of the moving image are transferred to the data compression unit. 2. Description of the Related Art An encoding device has been conventionally known (Japanese Patent Laid-Open No. 8-46519).

In this conventional image compression encoding apparatus, a 4: 2: 2 image signal reproduced by a D1-VTR for recording and reproducing in a known D1 format is converted into a 4: 2: 0 image signal by a specification conversion circuit. After the conversion, the data is written to the frame memory and supplied to the additional information detection unit to detect additional information (motion vector information and mode determination information required for motion compensation prediction) required for moving image compression coding. The multiplexer uses the 4: 2: 0 from the frame memory described above.
The image signal is output alternately in odd fields and even fields. In odd fields, luminance signal pixels and color difference signal pixels are alternately arranged for each pixel. In even fields, the luminance signal and the additional information from the additional information detection unit are output. Are taken out as a data sequence alternately arranged for each pixel and transferred to the data compression unit. In the data compression section, the 4: 2: 0 image signal and the additional information are separated by a demultiplexer, and the 4: 2: 0 image signal is compression-coded using the additional information.

[0004] In this conventional image compression encoding apparatus, 4:
When a 2: 2 image signal format is converted to 4: 2: 0, a 4: 2: 0 image such as MPEG is compressed by effectively utilizing a portion where the color difference signal pixel data of one screen is reduced by half. Parameter information required for encoding is multiplexed.

Next, the compression system MP used here
EG will be described. MPEG was established in 1988 by the ISO
/ IEC JTC1 / SC2 (International Organization for Standardization / Technical Committee of International Electrotechnical Commission / Technical Committee 2; current SC
29) The name of the organization that considers the moving picture coding standard established in (Moving Picture Experts)
Group). MPEG1 (MPEG phase 1) is a standard for storage media of about 1.5 Mbps, and JPEG for the purpose of still image encoding;
H.264 for video compression for low transfer rates of video conferencing and video telephony of Integrated Services Digital Network (ISDN). 261 (CCITT SGXV, current ITU-T
(Standardized by SG15), and a new technology is introduced for storage media. These were established in August 1993 as ISO / IEC 11172. MPEG2 (MPEG Phase 2)
In order to support various applications such as communication and broadcasting, the IS
O / IEC 13818; 262.

The format of an MPEG input image is M
The generally used profile of MP @ ML of PEG1 and MPEG2 is basically 4: 2: 0. 4: 2: 2 defined in ITU-R Recommendation 601
When the component format is schematically represented on a screen, a pixel of a luminance signal indicated by a white square in FIG.
/ 2 times that of MPEG2 above:
In the 2: 0 component format, as shown in FIG. 14B, the pixels of the color difference signal indicated by black circles are 倍 times the pixels of the luminance signal indicated by white squares in the vertical direction and the horizontal direction, respectively. ing. In FIG. 14, the pixel position indicates the phase.

As shown in FIG. 14C, the 4: 2: 0 component format of MPEG1 differs from the 4: 2: 2 component format in that a pixel of a luminance signal represented by a white square is represented by a black circle. The point that the pixels of the indicated color difference signal are halved in each of the vertical direction and the horizontal direction is similar to the 4: 2: 0 component format of MPEG2, but 4: 2: 0 of MPEG2.
The pixel position (phase) of the color difference signal differs from the component format.

In any case, the 4: 2: 0 component signal has half the vertical resolution of the 4: 2: 2 component signal and the number of pixels of the color of the digital data is also half. Absent. As is well known, the human eye thins out the number of pixels of the color difference signal at the time of inputting the MPEG coding based on the experimental result that the recognition ability of the color resolution is smaller than the luminance.

[0009] The encoding part of MPEG is created by combining several techniques. FIG. 15 is a block diagram showing an example of an image compression / encoding device using MPEG. In the figure, an input image is decoded by a motion compensation predictor 1 and a difference between the motion compensated prediction image and the input image is calculated by a subtraction circuit 2 to reduce a time redundant portion. The prediction direction is past,
In the future, there are three modes from both. These are 1
It can be switched and used for each MB (macroblock) of 6 pixels × 16 pixels. The prediction direction is determined by the picture type given to the input image. Picture type is P
There are pictures, B pictures, and I pictures. Prediction from the past and independent encoding of the MB without prediction 2
A P-picture exists in a mode. B-pictures have four modes for prediction from the future, prediction from the past, prediction from both, and independent encoding. It is an I picture that all MBs are independently encoded.

[0010] Motion Compensation (MC)
Predicts a motion vector with half-pel accuracy by performing pattern matching on a motion area for each MB, and shifts the motion vector by the amount of motion to predict the motion vector. The motion vector has a horizontal direction and a vertical direction, and is transmitted as additional information of the MB together with the MC mode indicating where to predict the motion vector. GOP (Group Of) from the I picture to the picture before the next I picture
Picture), when used in storage media or the like, generally about 15 pictures are used.

The difference image signal extracted from the subtraction circuit 2 is subjected to orthogonal transformation in a DCT unit 3. Discrete Cosine Transform (DCT) is an orthogonal transform that discretely transforms an integral transform using a cosine function as an integral kernel into a finite space. In MPEG, two-dimensional DCT is performed on an 8 × 8 DCT block obtained by dividing an MB into four. In general, since a video signal has many low-frequency components and few high-frequency components, when DCT is performed, coefficients concentrate on low frequencies.

[0012] DCT image data (DCT coefficients)
Are quantized by the quantizer 4. In this quantization, a value obtained by multiplying an 8 × 8 two-dimensional frequency called a quantization matrix by a visual characteristic by a value called a quantization scale for multiplying the whole by a scalar is used as a quantization value.
Divide the T coefficient by its quantized value. When inverse quantization is performed by the decoder, the original DCT is obtained by multiplying by the quantization value.
You will get a value that is close to the coefficient.

The quantized data is variable-length coded by a VLC unit 5. The direct current (DC) component of the quantized value is a DPCM (Differential Pulse) which is one of predictive coding.
se Code Modulation). In addition, Huffman coding in which an alternating current (AC) component performs a zigzag scan from a low frequency band to a high frequency band, assigns a run length of zero and an effective coefficient value to one event, and assigns a code having a short code length to a code having a high occurrence probability. Is performed. The variable-length coded data is stored in a temporary buffer 6 and output as coded data at a predetermined transfer rate.

The generated code amount of the output data for each macroblock is supplied to a code amount controller 7 and the error code amount between the generated code amount and the target code amount is fed back to the quantizer 4. The code amount is controlled by adjusting the quantization scale. The quantized image data is inversely quantized by an inverse quantizer 8, inversely DCTed by an inverse DCT 9, temporarily stored in an image memory 11 through an adder circuit 10, and then temporarily stored in a motion compensation predictor 1. , Is used as a reference decoded image for calculating a difference image. The output signal of the motion compensation predictor 1 is input to a subtraction circuit 2 and an addition circuit 10.

The encoded bit stream output from the buffer 6 has a variable length code amount for each picture in the case of video. This is because MPEG uses DCT, quantization,
At the same time that the information conversion called Huffman coding is used, it is necessary to adaptively change the code amount allocated to each picture in order to improve image quality. This is because since the motion compensation prediction is performed, the entropy of the coded image itself greatly changes, for example, in some cases, the input image is coded as it is, and in some cases, the difference image, which is the difference between the predicted images, is coded. In this case, in many cases, the code amount is controlled while allocating to the entropy ratio of the image and keeping the buffer limit. The limitation of this buffer is to encode the buffer on the decoding device side so that neither overflow nor underflow occurs.
ing Verifier).

FIG. 16 is a block diagram showing an example of a decoding device for coded data compressed and coded by MPEG.
In the figure, encoded data compressed and encoded by MPEG is variable-length decoded by a VLD unit 15 and then multiplied by a quantization width by an inverse quantizer 16 to obtain the original DC data.
After the value is approximated to the T coefficient, it is supplied to the inverse DCT unit 17 and subjected to inverse DCT to be locally decoded.

The motion vector and the prediction mode extracted from the inverse quantizer 16 are supplied to the motion compensation predictor 18 together with the decoded data from the image memory 20, and the motion compensated and predicted image data is output therefrom. Let it. The adder 19 receives the data from the inverse DCT unit 17 and the motion compensation predictor 1
8 to decode the image data equivalent to the image data input to the encoding device by adding the motion compensated image data from
0 and output to the outside.

[0018]

In the conventional image compression encoding apparatus conforming to the MPEG system shown in FIG. 15, compression encoding is performed in the 4: 2: 0 format as described above. On the other hand, a typical digital VTR for home use is D
There is a VC (Digital Video Cassette). DVC is MP
It is a compression method different from EG, and there are an SD standard for the current system and an HD standard for HDTV. In the SD system, the input image format is a 4: 1: 1 component format in NTSC. As shown in FIG. 14D, the 4: 1: 1 component format is different from the 4: 2: 2 component format in that the pixels of the luminance signal indicated by white squares and the pixels of the color difference signals indicated by black circles are horizontal. 1/2 times in the direction (1/4 of the input image)
Times) and the vertical direction is the same.

Here, a case is considered in which a 4: 2: 2 image signal is recorded on a DVC, and is further output from the DVC and copied to an application using MPEG encoding. When the image data encoded by DVC is decoded, the DVC format is 4: 1: 1.
The pixel interval of the color difference signal is 1/4 in the horizontal direction with respect to the pixel interval of the luminance signal. When this signal is re-encoded by 4: 2: 0 MPEG coding,
The vertical direction of the 4: 1: 1 image signal is further reduced to 、, and the number of pixels is 4: 1: 0 even though the same number of color difference signal pixels as the 4: 2: 0 image signal exists. The same color difference signal band as the image signal, that is, the number of pixels of the color difference signal is equivalent to a signal format in which the number of pixels in the luminance signal is ４ in the horizontal direction and は in the vertical direction. .

FIG. 17A is a conceptual diagram of the number of pixels of a 4: 2: 2 image signal, and FIG. 17B is a conceptual diagram of the number of pixels of a 4: 2: 0 image signal. FIG. 4C shows a conceptual diagram of the number of pixels of the image signal. The image signal obtained by re-encoding the 4: 1: 1 image signal by the MPEG encoding apparatus is 4 times smaller than the 4: 2: 2 image signal. As shown in FIG. 17D, the 4: 1: 0 image signal and the 4: 2: 0 image signal have poor horizontal and vertical color difference signals (Cb, Cr).
This means that the band is the same as that of an image having only the number of pixels of 0 image signal. As described above, conventionally, there is a problem in that the encoding of a format different from the color difference signal format causes a significant deterioration of the color difference signal.

The conventional image compression / encoding device described in Japanese Patent Application Laid-Open No. 8-46519 discloses a conventional image compression / encoding device which converts a 4: 2: 2 image signal format into a 4: 2: 0 image signal format. By effectively utilizing the part where the color difference signal pixel data of the screen has been reduced by half, and multiplexing parameter information necessary for compression-coding a 4: 2: 0 image signal such as MPEG, a system is realized. Although there is an effect of not complicating the bus line control when transferring the necessary additional information to the data compression unit, this conventional apparatus does not disclose any means for reducing the deterioration of the color difference signal of the image. Not.

The present invention has been made in view of the above points,
An object of the present invention is to provide a compression encoding method, a compression decoding method, a compression encoding device, and a compression decoding device capable of reducing deterioration of a color difference signal of image encoded data when a component format is changed and compression encoded. And

[0023]

In order to achieve the above object, a compression encoding method according to the present invention is directed to a compression encoding method for compressing and encoding an image signal in a first component format and outputting the image signal. After performing pixel replacement for replacing the pixel position of the color difference signal in the input image signal of the component format with a pixel position equivalent to the pixel position of the color difference signal in the image signal of the first component format, the compression coding of the input image signal is performed. Is performed.

In order to achieve the above object, the present invention provides a compression encoding method for compressing and encoding an image signal in a first component format and outputting the compressed image signal in a second component format. It is determined whether the frame correlation or the field correlation is higher for each predetermined area of the image signal. If the frame correlation is higher, the pixel position of the color difference signal in the input image signal of the second component format is determined by the first component format. Pixel replacement in a frame to be replaced with a pixel position equivalent to the pixel position of the color difference signal of one frame in the image signal of the second frame, and when the field correlation is higher, the color difference signal in the input image signal of the second component format Pixel position of the first component format image signal After performing replacement pixels in the field to replace the pixel position equivalent to a pixel position of the color difference signal of each field, and performs compression coding of the input image signal.

Here, in a compression encoding method for compressing and encoding an image signal in the first component format according to the MPEG system and outputting the image signal, after performing the above pixel replacement, the input image signal is subjected to frame correlation and The compression coding of the MPEG system may be performed according to the higher correlation among the field correlations. In this case, the vertical correlation of the picture after pixel replacement becomes high.

Here, the first component format is a 4: 2: 0 component format, the second component format is a 4: 1: 1 component format, and the input image signal is
It is characterized by performing compression coding in accordance with the EG system.

The first component format is a 4: 1: 1 component format, the second component format is a 4: 2: 0 component format, and the input image signal is converted to a DV format.
It is characterized by performing compression coding conforming to C.

According to another aspect of the present invention, there is provided a compression / decoding method for compressing and encoding an image signal in a first component format. The pixel position of the color difference signal of the first component format is replaced with a pixel position equivalent to the pixel position of the color difference signal in the image signal of the first component format. A compression decoding method for compressing and decoding in a component format of a first component format, wherein the pixel position of a color difference signal in a decoded signal of a first component format is received, and a pixel position of a color difference signal in the decoded signal of a first component format is received. A decoded signal in which pixel replacement for replacing the pixel position of the color difference signal in the input image signal with the same pixel position is output. To.

According to another aspect of the present invention, there is provided a compression encoding apparatus for compressing and encoding an image signal in a first component format and outputting the image signal. A pixel replacement unit that replaces the pixel position of the color difference signal in the image signal with a pixel position equivalent to the pixel position of the color difference signal in the image signal of the first component format, and converts the output image signal of the pixel replacement unit into a first component An encoder for compression-encoding in a format and multiplexing means for multiplexing and outputting an identification code indicating that pixel replacement has been performed in an output coded signal of the encoder.

Further, in the above-mentioned compression encoding apparatus of the present invention, a correlation judging section for judging which of the frame correlation and the field correlation is higher for each predetermined area of the input image signal of the second component format is provided. Based on the determination result of the determination unit, the pixel replacement of the pixel replacement unit may be performed in a picture having a higher correlation.

Further, in order to achieve the above object, the compression / decoding device of the present invention provides a coding device for compressing and coding an image signal in a first component format by converting an input image signal of a second component format into an input image signal. The pixel position of the color difference signal of the first component format is replaced with a pixel position equivalent to the pixel position of the color difference signal in the image signal of the first component format. A decoder for compression-decoding in the first component format, and a pixel position of the color difference signal in the decoded signal in the first component format, which receives the decoded signal output from the decoder, and The same pixel position as the pixel position of the color difference signal in And having a pixel replacement for outputting.

Further, in order to achieve the above object, the compression / decoding device of the present invention receives a compression-encoded signal together with identification information indicating which of a field correlation and a frame correlation is used for compression-encoding, A decoder for compressing and decoding in a first component format, a decoder for decoding output from the decoder and identification information are received, and an input decoded signal performs pixel replacement in a frame by the identification information. If it is determined that the pixel position is obtained, the pixel position of the color difference signal in the decoded signal of the first component format is changed to a pixel position equivalent to the pixel position of the color difference signal of one frame in the image signal of the second component format. If pixel replacement is performed in the frame to be replaced and pixel replacement in the field is determined, the first Pixel replacement for performing pixel replacement in a field that replaces the pixel position of the color difference signal in the decoded signal of the component format with a pixel position equivalent to the pixel position of the color difference signal of one field in the image signal of the second component format And a container.

In the present invention, when the input image signal of the second component format is a 4: 1, 1 component format such as DVC, and is re-encoded into a 4: 2: 0 component format such as MPEG, Equivalently, the MPE does not have the same band as an image having only the number of pixels of the signal of 4: 1: 0.
The band of the G output image signal can be reproduced while maintaining almost the same vertical band characteristics as the 4: 1: 1 component format.

Also, by replacing the chrominance signal pixels with the picture having the higher correlation between the frame correlation and the field correlation, the vertical correlation of the replaced picture can be increased.

[0035]

Next, an embodiment of the present invention will be described with reference to the drawings. First, the concept of the present invention will be described with reference to FIG. In the conceptual diagram of the number of pixels in FIG. 17, the area indicates the number of pixels per screen, and in the 4: 2: 2 (component format) image signal, FIG.
As shown in the figure, the number of pixels of the color difference signals Cb and Cr on one screen is に 対 し て of the horizontal direction and the same in the vertical direction as compared with the number of pixels of the luminance signal Y. Also 4:
In the 2: 0 image signal, as shown in FIG. 17B, the number of pixels of the color difference signals Cb and Cr on one screen is 、 of the horizontal direction and the number of pixels of the 1 in the direction
/ 2.

In the case of a 4: 1: 1 image signal, FIG.
As shown in (C), the number of pixels of the color difference signals Cb and Cr on one screen is 1/4 of the number of pixels of the luminance signal Y with respect to the horizontal direction, and is the same in the vertical direction. . Furthermore,
In the 4: 1: 0 image signal, as shown in FIG.
The number of pixels of the color difference signals Cb and Cr in one screen is 1/4 in the horizontal direction and 1/4 in the vertical direction as compared with the number of pixels in the luminance signal Y.

Accordingly, as can be seen from FIGS. 17B and 17C, the number of pixels (area) of the color difference signals (Cb, Cr) of the 4: 2: 0 image signal and the 4: 1: 1 image signal is respectively equal. The present embodiment pays attention to this fact, and performs pixel replacement so as to convert a color difference signal of the 4: 1: 1 component format as if it were a color difference signal of the 4: 2: 0 component format. It was made.

That is, as described above, when the original compression-encoded image data is an image signal of a 4: 1: 1 component format and is converted to an image signal of a 4: 2: 0 component format, a simple , The number of pixels in the vertical direction of the color difference signal of the 4: 1: 1 image signal is further reduced to 、, and the number of pixels is the same as that of the 4: 2: 0 image signal. Nevertheless, the number of pixels of each of the two color difference signals is 1/4 of the number of pixels of the luminance signal in the horizontal direction, which is the same as the 4: 1: 0 image signal.
In addition, the vertical direction is equivalent to a signal format that is reduced to half.

Therefore, in this embodiment, in order to avoid this, the pixels are replaced, and whether the color difference signal in the 4: 1: 1 image signal is a color difference signal in the 4: 2: 0 image signal is determined. In this way. This is a method in which the phase of the actual image is ignored, but the phase is restored if this inverse transformation is always performed when outputting. In addition, since compression is involved, encoding degradation may spread, but in order to minimize degradation, by increasing the encoding rate,
Can avoid enough.

For example, when DVC is about 25 Mbps, 4:
Because of the 1: 1 component format, the output compression-encoded image data is converted to about 8 Mb on a DVD using the MPEG2 compression of the 4: 2: 0 component format.
In the case of recording in ps or the like, no matter how high the coding rate is used unless this embodiment is used, the band becomes 4: 1: 0 component format on the format, and the vertical resolution is reduced to about half. turn into.
In the case of a moving image, field processing is performed to halve the number of pixels in the vertical direction in the field, so that the vertical resolution characteristic in the moving image band is reduced to 1/4. But,
By using the present invention, if a general image is used, M
At a coding rate of 8 Mbps in PEG2 compression, coding deterioration hardly occurs. Therefore, decoding can be performed while maintaining the vertical resolution of the 4: 1: 1 image signal by returning the pixel replacement of the present invention in the reverse order.

Next, a method of converting a chrominance signal of a 4: 1: 1 component format into a chrominance signal of a 4: 2: 0 component format (hereinafter referred to as a “chrominance signal 411/420 pixel replacement method”) will be described.
This will be specifically described. The chrominance signal 411/420 pixel replacement method can be roughly divided into two methods, a method of replacing within a frame picture and a method of replacing within a field picture.
There are types.

FIGS. 1A and 1B are diagrams for explaining the first and second embodiments of the image compression / encoding method according to the present invention, and both show color difference signals 411 in a field picture.
The following describes a / 420 pixel replacement method. 1A and 1B show the pixel positions on the screen of a 4: 1: 1 image signal, where a white square indicates a pixel of a luminance signal, a black circle indicates a pixel of a color difference signal, and gray Indicates a pixel of the color difference signal after being replaced by a pixel position where only the luminance signal exists. In the actual 4: 1: 1 image signal, for example, 360 pixels (0 to 359 in the horizontal direction) × 480 lines (0 to 479 in the vertical direction) are present on the screen. This represents a portion of eight lines (the same applies to FIG. 2 described later).

The color difference signal pixel replacement method shown in FIG. 1A is used when the pixel number counted from 0 is divisible by 4, and the line number is divided by 4 and the remainder is 2 to obtain the color difference signal at the pixel position in the first field. The pixel is replaced so as to be shifted by two pixels to the right and by two pixels upward, and when the pixel number is divisible by 4, the line number is divided by 4 and the remainder is 3 The pixel of the color difference signal is shifted by two pixels to the right and by two pixels upward (however, the pixel number 0 is divisible by 4).

Thus, for example, the pixel number 0 of the first field and the third (line number 2) color difference signal in the vertical direction have a pixel number divisible by 4 as shown by an arrow 21 in FIG. Since the line number is located at two extra pixel positions by dividing by 4, the image is shifted to the right by two pixels and upward by two pixels to be shifted to the pixel position of pixel number 2 and line number 0. Similarly, for example, pixel number 0 in the second field and vertical direction 4
As shown by an arrow 22 in FIG. 1A, the color difference signal of the third (line number 3) is located at the pixel position where the pixel number is divisible by 4 and the line number is divided by 4 and is 3 extra pixels. The image data is shifted upward by two pixels and by two pixels, and shifted to the pixel position of pixel number 2 and line number 1.

According to this pixel replacement method, 4: 1:
Each pixel of a color difference signal existing in a line number that is divisible by 4 and which is 2 or 3 extra line numbers when divided by 4 in one image signal is a pixel number that can be divided by 4 or divided when 4 Is shifted to a pixel position where no color difference signal exists, and as a result, the pixel array is replaced with a pixel array equivalent to the pixel position of the color difference signal of the 4: 2: 0 image signal.

The color difference signal pixel replacement method shown in FIG. 1B is used when the pixel number counted from 0 is divisible by 8, and the line number is divided by 4 and left by 2 at the pixel position in the first field. The pixels of the color difference signal are replaced so as to be shifted by two pixels to the right and by two pixels upward, and the pixel position of the first field where the line number is divisible by 4 when the pixel number is divided by 8 Are shifted to the right by two pixels, and then two pixels below are shifted to the current position (up) by two pixels. Also,
The pixel of the chrominance signal at the pixel position of the second field where the pixel number is divisible by 8 and the line number is divided by 4 and is 3 extra is shifted right by two pixels and upward by two pixels. Further, the pixel of the color difference signal at the pixel position of the second field, which is 4 when the pixel number is divided by 8 and 1 when the line number is divided by 4, is shifted to the right by 2 pixels.
In this method, two pixels below are shifted to the current position (up) by two pixels (however, 0 is divisible by 4).

Therefore, for example, the first color difference signal (line number 0) in the vertical direction with the pixel number 4 is located at the pixel position of the first field where the pixel number is divisible by 8 and the line number is divisible by 4. As shown by an arrow 23 in FIG. 1B, the pixel is shifted to the right by two pixels, and is replaced by the position of the line number 0 with the pixel number 6 where the color difference signal pixel does not originally exist. The pixel of the color difference signal of the first field of the pixel number 4 and the line number 2 two pixels below the pixel of the number 0 is shifted as shown by an arrow 24 in FIG. Is shifted to the pixel position of pixel number 4 and line number 0 at the current position. A color difference signal pixel whose pixel number is divisible by 8 and whose line number is 2 or 3 more than 4 is shifted in the same manner as in FIG. By this pixel replacement method, as shown in FIG.
The 1: 1 image signal is replaced with a pixel array equivalent to the pixel position of the color difference signal of the 4: 2: 0 image signal.

FIGS. 2A and 2B are explanatory diagrams of the third and fourth embodiments of the image compression / encoding method according to the present invention.
A 420 pixel replacement method will be described. FIG. 2 (A) and (B)
Indicate the pixel positions on the screen of the 4: 1: 1 image signal, white squares indicate luminance signal pixels, black circles indicate color difference signal pixels, and gray circles indicate color difference signal pixels. The pixel of the color difference signal replaced with a pixel position that does not exist is shown.

The color difference signal pixel replacement method shown in FIG. 2A is used when the pixel number counted from 0 is divisible by 4, and the pixel of the color difference signal at the pixel position where the line number is divided by 2 and is 1 or 3 extra pixels. , Two pixels to the right and one pixel upward (the pixel number 0 is divisible by 4). Therefore, for example, the second color difference signal (line number 1) in the vertical direction at pixel number 0 is obtained by dividing the pixel number by 4 and dividing the line number by 2 as shown by an arrow 26 in FIG. Since there is one more pixel position, the pixel position is shifted to the right by two pixels and upward by one pixel and shifted to the pixel position of pixel number 2 and line number 0. Similarly, for example, the fourth color difference signal (line number 3) in the vertical direction at pixel number 0 is obtained by dividing the pixel number by 4 and dividing the line number by 2 as shown by an arrow 27 in FIG. Since there is one more pixel position, the pixel position is shifted to the right by two pixels and upward by one pixel and shifted to the pixel position of pixel number 2 and line number 2.

According to this pixel replacement method, each pixel of the color difference signal existing in a line number that is divisible by 4 and one or three extra line numbers when divided by 4 is represented by two extra pixel numbers when divided by 4. 2 is shifted to a pixel position where a color difference signal does not exist in a line number divisible by 2, resulting in a pixel array equivalent to the pixel position of the color difference signal of the 4: 2: 0 image signal.

In the color difference signal pixel replacement method shown in FIG. 2B, the pixel number counted from 0 is located at a pixel position divisible by 8, and the line number is located at 1 or 3 extra pixel positions when divided by 4. The pixels of the color difference signal are replaced so as to be shifted by two pixels to the right and by one pixel upward. Further, when the pixel number is divided by 8, the remaining four pixels are divided by two and the line number of the color difference signal at the pixel position divisible by 2 Pixels are shifted to the right by two pixels, and then shifted one pixel down to the current position (up) by one pixel (where 0 is divisible by 8).

Therefore, for example, the first color difference signal (line number 0) in the pixel number 4 in the vertical direction (line number 0) is located at a pixel position where the pixel number is divided by 8 and the remainder is 4 and the line number is divisible by 2. As shown by an arrow 28 in (B), the pixel is shifted to the right by two pixels, and is replaced by the position of line number 0 with the pixel number 6 where the color difference signal pixel does not originally exist, and then the pixel number 4 and the line number 0 The pixel of the color difference signal of the pixel number 4 and the line number 1 below the pixel of the pixel No. is shifted as indicated by an arrow 29 in FIG. 2B, and the pixel at the current position where the color difference signal pixel no longer exists. The pixel number is shifted to the pixel position of line number 0. A color difference signal pixel whose pixel number is divisible by 8 and whose line number is divided by 2 and left by one is shifted in the same manner as in FIG. By this pixel replacement method, as shown in FIG. 2B, the color difference signal of the 4: 1: 1 image signal is changed to 4: 2: 0.
The pixel arrangement is equivalent to the pixel position of the color difference signal of the image signal.

Next, a method of converting a color difference signal of a 4: 2: 0 component format into a color difference signal of a 4: 1: 1 component format (hereinafter referred to as a “color difference signal 420/411 pixel replacement method”) will be described.
This will be specifically described. The chrominance signal 420/411 pixel replacement method performs the reverse operation of the chrominance signal 411/420 pixel replacement method. This method is also roughly divided into a method of replacing within a frame picture and a method of replacing within a field picture. There are two types.

FIGS. 3A and 3B are explanatory diagrams of the first and second embodiments of the image compression / decoding method according to the present invention, and both show color difference signals 420 in a field picture.
The / 411 pixel replacement method will be described. 3A and 3B show the pixel positions of 4: 2: 0 image signals on the screen, in which white squares indicate luminance signal pixels, black circles indicate color difference signal pixels, and gray Indicate the pixel of the color difference signal after replacement. The actual 4: 2: 0 image signal is, for example, 360 pixels (0 to 359 in the horizontal direction) ×
FIG. 3 shows a portion of 4 pixels × 8 lines where 480 lines (0 to 479 in the vertical direction) exist (the same applies to FIG. 4 described later).

The color difference signal pixel replacement method shown in FIG. 3A is when the pixel number counted from 0 is divided by 4 and left over, and the pixel of the color difference signal of the first field whose line number is divisible by 4 is: If the pixel number is divided by 4 and the remainder is 2 and the line number is divided by 4 and the remainder is 1 then the pixel is shifted by 2 pixels to the left and down by 2 pixels. , Two pixels downward (provided that pixel number 0 is divisible by 4).

Therefore, for example, the first color difference signal (line number 0) of pixel number 2 in the vertical direction (line number 0) is located at a pixel position where the pixel number is divided by 4 and the remainder is 2 and the line number is divisible by 4. As shown by an arrow 31 in (A), the image data is shifted to the left by two pixels and downward by two pixels to the pixel position of pixel number 0 and line number 2. Similarly, for example, the second color difference signal (line number 1) in the vertical direction at pixel number 2 has a pixel number of 4 as indicated by an arrow 32 in FIG.
Is divided by two and the line number is divided by four, so that it is shifted by two pixels to the left and by two pixels to the pixel position of pixel number 0 and line number 3. You. According to this pixel replacement method, the color difference signal of the 4: 2: 0 image signal replaced by the method of FIG. 1A is replaced with a pixel array equivalent to the pixel position of the color difference signal of the 4: 1: 1 image signal. .

Also, the color difference signal pixel replacement method shown in FIG. 3B is used when the pixel number counted from 0 is divided by 8 and the remainder is 2 and the line number is divisible by 4.
When the pixel number is shifted by two pixels to the left and shifted downward by two pixels, and when the pixel number is divided by 8 and there are 4 remaining,
When the line number is divisible by 4, shift down by 2 pixels, then move the two right pixels to the current position (to the left)
Shift by one pixel. When the pixel number is divided by 8 and the remainder is two, and when the line number is divided by four and the remainder is one, the pixel is shifted left by two pixels and downward by two pixels. When the pixel number is divided by 8 and the remainder is 4 and the line number is divided by 4 and the remainder is 1, the pixel is shifted downward by two pixels, and then the pixel two right to the current position ( (To the left) A method of shifting by two pixels (however, 0 is divisible by 4).

Accordingly, for example, the first color difference signal (line number 0) in the pixel number 4 in the vertical direction (line number 0) is located at a pixel position where the pixel number is divided by 8 and the remainder is 4 and the line number is divisible by 4. As shown by an arrow 33 in (B), the pixel is shifted downward by two pixels, and is replaced by the position of line number 2 with the pixel number 4 where the color difference signal pixel does not exist, and then the pixel number 4 and the line number 0 The pixel of the color difference signal of the pixel number 6 and the line number 0 which is two pixels to the right of the pixel at the current position where the color difference signal pixel no longer exists is shifted as indicated by an arrow 34 in FIG. The pixel number is shifted to the pixel position of line number 0. Further, a color difference signal pixel at a position where the pixel number is divided by 8 and the remainder is 2 and the line number is divisible by 4 or the remainder is 1 is shifted in the same manner as in FIG. By this pixel replacement method, FIG.
4: 2: 0 pixel replaced by method (B)
As shown in FIG. 3B, the color difference signal of the image signal is 4:
It is replaced with a pixel array equivalent to the pixel position of the color difference signal of the 1: 1 image signal.

FIGS. 4A and 4B are explanatory diagrams of the third and fourth embodiments of the image compression / decoding method according to the present invention.
A method for replacing 411 pixels will be described. FIG. 4 (A) and (B)
Indicate the pixel positions on the screen of the 4: 2: 0 image signal, white squares indicate luminance signal pixels, black circles indicate color difference signal pixels, and gray circles indicate color difference signals after replacement. Pixel.

The color difference signal pixel replacement method shown in FIG. 4A is performed when the pixel number counted from 0 is divided by 4 and there are two remainders, and when the line number is divisible by 2, two pixels to the left and downward are used. In this method, the pixel number is shifted by one pixel (however, the pixel number 0 is divisible by 2).

Therefore, for example, the first color difference signal (line number 0) in the pixel number 2 in the vertical direction is at a pixel position where the pixel number is divided by 4 and the remainder is 2 and the line number is divisible by 2. As shown by an arrow 36 in (A), the image data is shifted to the left by two pixels and downward by one pixel to the pixel position of pixel number 0 and line number 1. Similarly, for example, the third color difference signal (line number 2) in the vertical direction at pixel number 2 is at the pixel position where the pixel number is divided by 4 and the remainder is 2 and the line number is divisible by 2; ), The image data is shifted to the left by two pixels and downward by one pixel to the pixel position of pixel number 0 and line number 3. With this pixel replacement method, the color difference signal of the 4: 2: 0 image signal whose pixel has been replaced by the method of FIG. 2A is converted into a pixel array equivalent to the pixel position of the color difference signal of the 4: 1: 1 image signal. Be replaced.

Further, the color difference signal pixel replacement method shown in FIG. 4B is for the case where the pixel number counted from 0 is divided by 8 and the remainder is 2 and when the line number is divisible by 2, 2 pixels to the left are used. If the pixel number is divided by 8 and the remainder is 4 and the line number is divisible by 2, it is shifted down by one pixel and then shifted down by one pixel, and then shifted right by two pixels. Is shifted to the current position (to the left) by two pixels (however, 0 is divisible by 2).

Therefore, for example, the first color difference signal (line number 0) in the pixel number 4 in the vertical direction is located at a pixel position where the pixel number is divided by 8 and the remainder is 4 and the line number is divisible by 2. As shown by an arrow 38 in (B), the pixel is shifted downward by one pixel, and is replaced with the position of line number 1 by the pixel number 4 where the color difference signal pixel does not originally exist, and subsequently, the pixel number 4 and the line number 0 The pixel of the color difference signal of the pixel number 6 and the line number 0 two pixels to the right of the pixel at the current position where the color difference signal pixel no longer exists is shifted as indicated by an arrow 39 in FIG. The pixel number is shifted to the pixel position of line number 0. A color difference signal pixel at a position where the pixel number is divided by 8 and the remainder is 2 and the line number is divisible by 2 is shifted in the same manner as in FIG. According to this pixel replacement method, the color difference signal of the 4: 2: 0 image signal whose pixel is replaced by the method of FIG. 2B is changed to the color difference signal of the 4: 1: 1 image signal as shown in FIG. The pixel arrangement is equivalent to the pixel position of the signal.

In the above description, for the sake of convenience, chrominance signal 411/420 pixels are replaced in the image compression coding.
Although the description has been made assuming that the color difference signal 420/411 pixel replacement is performed in the image compression decoding, the reverse is true (that is, the color difference signal 411/420 pixel replacement is performed in the image compression decoding, and the color difference signal 420/411 pixel replacement is performed in the image compression encoding). )
Needless to say, it may be.

Next, embodiments of the compression encoding apparatus and the compression decoding apparatus according to the present invention will be described with reference to the drawings. FIG. 5 is a block diagram showing a first embodiment of the compression encoding apparatus according to the present invention. In the figure, 4: 1: 1
The image signal is converted into a color difference signal 411/420 format converter 41 and a color difference signal 411/420 pixel replacement unit 42.
Respectively.

The color difference signal 411/420 format converter 41 oversamples the input 4: 1: 1 image signal in the horizontal direction to double the number of horizontal pixels. In addition, after performing filtering to reduce the band to １ ／ in the vertical direction, the number of samplings is halved. Color difference signal 41
The 1/420 pixel replacement unit 42 is arbitrarily set to any of the color difference signal 411/420 pixel replacement methods described with reference to FIGS. 1A and 1B and FIGS. 2A and 2B. Alternatively, the color difference signal 411/420 pixels are replaced by one predetermined method.

The color difference signal 411/420 pixel replacement unit 42 separates the color difference signals from, for example, the input 4: 1: 1 image signal and sequentially writes them in a memory under the control of an address controller. The stored color difference signal data is read out from the memory in the order of addresses that realizes the color difference signal 411/420 pixel replacement method described with reference to FIG. 2 and written again into the memory, and then the color difference signal data read out from the memory is input. In this configuration, luminance signal data separated from a 1: 1 image signal is synthesized and output.

The color difference signal 411/420 format converter 41 and the color difference signal 411/420 pixel replacement unit 42
Are respectively supplied to a switch circuit (S / W) 44, where a user interface 43
, The image signal of the method specified by the user is selected. In this case, when decoding is performed using the decoding device of the present invention described below,
The color difference signal 411/420 is equivalently 4: 2: 0 component format from the pixel replacement unit 42,
The S / W 44 is switched so that the 4: 2: 0 image signal is selected. On the other hand, when decoding a digital signal that has been compression-encoded by an existing decoding apparatus having no pixel replacement means according to the present invention, the chrominance signal 411/4 is used.
The S / W 44 is switched so that the image signal taken out of the 20 format converter 41 and having a band of 4: 1: 0 component format is selected.

The image signal selected by S / W 44 is M
The data is input to the PEG encoder 45 and compression-coded in accordance with the MPEG system of the 4: 2: 0 component format. The MPEG encoder 45 has a known configuration shown in FIG. The input image signal of the MPEG encoder 45 is originally in the 4: 1: 1 component format. However, when the pixel replacement is performed by the color difference signal 411/420 pixel replacement unit 42, the color difference signal is as if it were 4 pixels. : 2: 0 component format is converted as if it were a color difference signal, so that it does not become like a 4: 1: 0 image signal by encoding as in the prior art, but as a 4: 2: 0 image signal. Taken out. The bit stream encoded and taken out by the MPEG encoder 45 is supplied to a buffer memory and formatter 46.

On the other hand, the synchronization control section 47 has a timer for a predetermined period, and outputs a trigger signal to the synchronization signal generator 48 every predetermined period. This predetermined period is, for example, NTSC
It is selected to be 1 / 29.97 seconds, which is one frame period of the system image signal. When detecting the input of the trigger signal from the synchronization control unit 47, the synchronization signal generation unit 48
U is set as an area in which data unrelated to video and audio can be embedded using PEG syntax.
A synchronization signal having a fixed pattern that can be uniquely identified in advance and that indicates the presence of the identification code of the present embodiment in a predetermined area such as ser_data is generated.

For example, the MPEG1 video stream picture layer is defined as shown in FIG.
A mechanism is defined such that the user data (user_data) can be transmitted in 8-bit units after the user data start code (user_data_start_code) is transmitted before the slice layer. Further, as shown in FIG. 13, a transport private data flag (trans) is also provided in a system layer of a transport stream such as MPEG2.
1 for sport_private_data_flag)
, Private data (private_d
data), and the data length does not exceed the transport packet.
Transport Private Data Length (t
transport_private_data_len
gth) of the private data (p
drive_data) can be transmitted.

In addition to the above, another method of transmitting user-specific data in the MPEG system is a stream id (st
private stream (priv
ate_stream) is set and the packet is transmitted by declaring a dedicated packet. For example, in the present embodiment, a synchronization signal or an identification code is multiplexed with coded data and transmitted for the purpose of transmission. , Any of those mechanisms may be used.

Here, user__ of MPEG1 video
Assuming that data is used, user_data_
start_code is 0x0 before the slice layer
00001B2. After transmitting the code, a synchronization signal that can be uniquely identified in advance, indicating the presence of an identification code described later in the user data area, is transmitted. This synchronization signal is set to a value (for example, 0x0f0f0f0f2428fdaa) determined separately from the MPEG standard, and has a purpose of causing the decoding apparatus to specify a position where an identification code described later is multiplexed after the synchronization signal. . Specifically, the generation timing of the synchronization signal is
After observing the MPEG stream input from the MPEG encoder 45 to the buffer memory and formatter 46, specify a predetermined user_data area, generate a user_data_start_code, and declare that the user_data area is the user_data area. Become.

The synchronization signal generator 48 shown in FIG. 5 outputs a signal indicating that a synchronization signal has been generated to the identification code generator 4.
9 is output. The identification code generator 49 outputs the buffer memory and the formatter 46 at the timing after the synchronization signal.
Is the input image signal processed by the color difference signal 411/420 format converter 41,
An identification code having a value indicating whether it has been processed by the 420 pixel replacement unit 42 is generated and supplied to the buffer memory and formatter 46.

The value of the identification code is determined based on a signal input from the user interface 43 via the synchronization signal generator 48. For example, one byte is prepared as the identification code. 420 indicates that the processing has been performed by the pixel replacement unit 42. If 0x00, the color difference signal 411/420 format converter 41
Indicates that it was processed by. The buffer memory and formatter 46 outputs to the data recording unit 50 the compression-encoded image data obtained by arranging the data in accordance with the format of the recording medium 51 and a digital signal composed of a synchronization signal and an identification code. It is recorded on an optical disk or other recording medium 51.

The chrominance signal 411/420 pixel replacement unit 42 uses two or more chrominance signal 411/420 pixel replacement methods out of the four types of chrominance signal 411/420 pixel replacement methods shown in FIGS. Is selectable, the type of color difference signal 411/42
Information indicating whether the 0-pixel replacement method is used is also included in the identification code.

Next, an example of a suitable decoding device for realizing the present invention will be described. FIG. 6 shows a block diagram of a first embodiment of the compression / decoding device according to the present invention. In the figure, the digital signal read from the recording medium 51 recorded by the image compression encoding apparatus of FIG.
3. The information is supplied to the identification code detection unit 54 and the MPEG decoder 55, respectively. The synchronization signal detection unit 53 is an MPEG
While observing the stream of
a area is specified, and then user_data_st
After detecting the art_code and confirming that it is a user_data area, a synchronous signal of a fixed pattern is detected.

The identification code detection section 54 receives the trigger signal output from the synchronization signal detection section 53 when the synchronization signal is detected, and synchronizes the identification code multiplexed in the predetermined area with the synchronization signal with the reproduced digital signal. Detected from inside,
It is transmitted to the color difference signal generation method determination unit 56. The color difference signal generation method determination unit 56 determines whether the reproduced digital signal has been processed by the color difference signal 411/420 format converter 41 in FIG.
2 is determined from the input identification code based on the input identification code, and a switch circuit (S / W) 57 is determined in accordance with the determination result.
, And supplies the determination result to the color difference signal output format converter 59.

That is, the color difference signal generation method determining section 56
When it is determined that the image data is processed by the color difference signal 411/420 pixel replacement unit 42, the image data decoded by the MPEG decoder 55 having a known configuration shown in FIG. The image data decoded by the MPEG decoder 55 is supplied directly to the color difference signal output format converter 59 when it is supplied to the replacement unit 58 and is determined to have been processed by the color difference signal 411/420 format converter 41. The switching control of the switch circuit (S / W) 57 is performed so as to supply the power to the switch.

Color difference signal 420/411 pixel replacement unit 5
Reference numeral 8 denotes an image signal recorded on the recording medium 51 in the color difference signal 420/411 pixel replacement method described with reference to FIGS. 3A and 3B and FIGS. 4A and 4B. The color difference signal 420/4 is obtained by one predetermined method corresponding to the color difference signal 411/420 pixel replacement method.
After 11-pixel replacement, the image signal is returned to the same 4: 1: 1 image signal as the original image signal input to the compression encoding device, and output.

That is, the chrominance signal 411/420 pixel replacement unit 42 of the compression encoder of FIG.
The color difference signal of one image signal is equivalent to the color difference signal array of the 4: 2: 0 image signal, and the color difference signal in the 4: 1: 1 image signal is as if the color difference signal in the 4: 2: 0 image signal. If the decoded signal of the signal encoded by the MPEG encoder 45 is output from the MPEG decoder 55 as if it were as described above, the color difference signal of the decoded signal differs from the phase of the original image. The color difference signal 411 /
420 Color difference signal 411/4 performed by pixel replacer 42
It is necessary to replace the 420/411 pixel of the color difference signal, which is the reverse of the 20 pixel replacement method, to restore the phase of the color difference signal.

Therefore, when the chrominance signal 411/420 pixel replacement unit 42 performs the chrominance signal 411/420 pixel replacement method of FIG.
The one-pixel replacement unit 58 outputs the color difference signal 420 shown in FIG.
/ 411 pixel replacement method needs to be performed.
The chrominance signal 411/420 pixel replacement method is shown in FIG.
(B), FIG. 2 (A), and FIG. 2 (B), the corresponding color difference signal 411/420 pixel replacement method shown in FIG. 3 (B), FIG. 4 (A), and FIG. 4 (B), respectively. Need to do.

The color difference signal output format converter 59
Based on the determination result from the color difference signal generation method determination unit 56, the same 4: 1: 1 image signal as that input to the compression encoding device by the color difference signal 420/411 pixel replacement unit 58.
When it is detected that the image signal returned to the image signal is input, the 4: 1: 1 image signal is oversampled twice in the horizontal direction, converted to a 4: 2: 2 image signal, and output. . On the other hand, the color difference signal output format converter 59
When it is detected based on the determination result from the color difference signal generation method determination unit 56 that the image signal output from the MPEG decoder 55 is directly input, the image signal is oversampled twice in the vertical direction. Output.

Therefore, if the image signal directly input from the MPEG decoder 55 to the chrominance signal output format converter 59 through the switch circuit 57 is a 4: 2: 0 image signal, it is converted to a 4: 2: 2 image signal. On the other hand, a signal output from the color difference signal output format converter 59 and MPEG-coded from the 4: 1: 1 image signal is converted into an MPEG decoder 55
In the case of the 4: 1: 0 image signal decoded in step (1), the image signal is output as it is.

Next, a second embodiment of the device of the present invention will be described. FIG. 7 is a block diagram showing a second embodiment of the compression encoding apparatus according to the present invention. 5, the same components as those of FIG. 5 are denoted by the same reference numerals, and the description thereof will be omitted.
In the first embodiment described above, the replacement of the color difference signal pixels in the frame picture or the replacement of the color difference signal pixels in the field picture is fixedly performed on the entire screen. In this example, the automatic switching is performed by using the frame / field correlation determination unit 61.

That is, the 4: 1: 1 image signal is supplied to the frame / field correlation determining section 61 shown in FIG. 7, where the frame / field correlation is determined for each predetermined area. 1 is obtained, the pixel of the color difference signal is replaced in the field picture as shown in FIGS. 1A and 1B, and if the determination result that the frame correlation is large is obtained as shown in FIG. (A),
The chrominance signal 411/420 pixel rewrite unit 42 is controlled according to the determination result so as to replace the pixel of the chrominance signal in the frame picture as in (B), and is converted into a 4: 2: 0 image signal.

The frame / field correlation judging section 6
The determination result from 1 is supplied to the identification code generation unit 62,
Whether the pixel of the color difference signal has been replaced in the field picture or the pixel of the color difference signal has been replaced in the frame picture is designated using another bit in the identification code.

The correlation determination by the frame / field correlation determination section 61 is performed, for example, in the image data of the specific area 81 in FIG. The difference sum (the value obtained by adding the difference value between the upper and lower two pixels for the pixels for one line) is calculated, and similarly, as indicated by 83, the second difference sum with the pixel below the two lines is calculated. , A method of determining that the smaller the sum of the differences is, the larger the correlation is. In FIG. 18, the first sum of differences indicates the magnitude of the frame correlation, and the second sum of differences indicates the magnitude of the field correlation.

FIG. 8 shows a third example of the compression encoding apparatus according to the present invention.
FIG. 2 is a block diagram of the embodiment. 5 and 7 in FIG.
The same components as those described above are denoted by the same reference numerals, and description thereof will be omitted. In this embodiment, the determination result of the frame / field correlation determination unit 61 in the second embodiment of FIG. 7 is supplied not to the identification code generation unit 62 (49) but to the MPEG encoder 64, and is used in MPEG. A frame / field correlation determination result is used for a macro block (16 pixels × 16 lines). MPE
The G encoder 64 receives the frame / field determination result, and the DCT unit 3 shown in FIG. 15 performs the determination on either the frame / field based on the input result. Is performed.

Thus, in this embodiment, the color difference signal pixel replacement method is performed on a picture in a frame or a field in accordance with the result of determining the magnitude of the frame or field correlation on a macroblock basis. In addition, the vertical correlation of the replaced picture is increased, and the encoding efficiency of MPEG compression is increased. Therefore, when encoding is performed at the same encoding rate, encoding can be performed with relatively high image quality.

The result of the determination is the DCT which is the macroblock layer of the video syntax of MPEG2 shown in FIG.
In which frame or field was performed (d in MPEG2 video coding syntax)
ct_type1 bit 0 is a frame when it is 0, or a field when it is 1, or a frame / field motion compensation mode (a field is set when the Frame_motion_type2 bit in the MPEG2 video coding syntax is 01, and a frame is set when 10 is 10). By using it, you do not have to send it.

FIG. 9 shows a second embodiment of the compression / decoding device according to the present invention.
FIG. 2 is a block diagram of the embodiment. 6, the same components as those of FIG. 6 are denoted by the same reference numerals, and the description thereof will be omitted. This second embodiment is an embodiment corresponding to the compression encoding device shown in FIG. 8, in which a reproduced digital signal from a buffer memory 52 is supplied to an MPEG decoder 68,
While being decoded, the DCT mode signal at that time is supplied to the color difference signal 420/411 pixel replacement unit 69.

Color difference signal 420/411 pixel replacement unit 6
FIG. 9A shows the case where the DCT mode is the field mode, the field correlation is large, and the input image signal is considered to have been rewritten by the chrominance signal 411/420 pixels in the field picture. As shown in (B), the color difference signal 420/4 in the field picture
When 11 pixels are replaced and the DCT mode is the frame mode, the correlation between frames is large, and it is considered that the chrominance signal 411/420 pixels have been rewritten in the frame picture. As shown in (B), the color difference signals 420/41 in the frame picture
One pixel replacement is performed.

FIG. 10 is a block diagram showing a fourth embodiment of the compression encoding apparatus according to the present invention. 5, the same components as those of FIG. 5 are denoted by the same reference numerals, and the description thereof will be omitted.
In this embodiment, a color difference signal in a 4: 2: 0 image signal is replaced with a 4: 1: 1 image signal and encoded. That is, in FIG. 10, the 4: 2: 0 image signal is supplied to the color difference signal 420/411 format converter 71 and the color difference signal 420/411 pixel replacement unit 72, respectively.

The color difference signal 420/411 format converter 71 halves the number of horizontal pixels of the input 4: 2: 0 image signal and oversamples twice in the vertical direction. The color difference signal 420/411 pixel replacement unit 72 is arbitrarily set to any of the color difference signal 420/411 pixel replacement methods described with reference to FIGS. 3A and 3B and FIGS. 4A and 4B. The color difference signal 420/411 pixels are replaced by one of the methods described above or one predetermined method.

The color difference signal 420/411 format converter 71 and the color difference signal 420/411 pixel replacement unit 72
Are respectively supplied to a switch circuit (S / W) 44, where a user interface 43
, The image signal of the method specified by the user is selected. Switch circuit 4
The 4: 1: 1 image signal selected by 4 is supplied to the DVC encoder 73, where the 4: 1: 1 image signal conforms to the DVC standard.
After being encoded in the 1: 1 component format, it is supplied to the buffer memory and formatter 74. In this embodiment, when the MPEG data is encoded as the DVC format, it can be reproduced while retaining the same horizontal band characteristics as the 4: 2: 0 component format.

FIG. 11 is a block diagram showing a third embodiment of the compression / decoding device according to the present invention. 6, the same components as those of FIG. 6 are denoted by the same reference numerals, and the description thereof will be omitted.
The third embodiment is an embodiment corresponding to the compression encoding device shown in FIG. 10, and a 4: 1: 1 image signal extracted from the buffer memory 52 is decoded by a DVC decoder 76. After that, it is supplied to the switch circuit 57.

The color difference signal 411/420 pixel replacement unit 7
Reference numeral 7 denotes a method for replacing the 4: 1: 1 image signal input from the switch circuit 57 with the chrominance signal 411/420 pixel described with reference to FIGS. 1A, 1B, 2A and 2B. Of these, the chrominance signal 411/420 pixel replacement is performed by one method corresponding to the encoding device side.

[0099]

As described above, according to the present invention,
The input image signal of the second component format is
This is a 4: 1: 1 component format such as DVC. If this is re-encoded into a 4: 2: 0 component format such as MPEG, it is equivalent to 4: 1: 1.
To reproduce the MPEG output image signal band while maintaining almost the same vertical band characteristics as the 4: 1: 1 component format without becoming the same band as the image having only the number of pixels of the 0 signal. Can be.

Also, according to the present invention, MPEG and the like 4:
Change 2: 0 component format and 4: 1:
When re-encoding to an application using DVC encoding of one component format, the DVC output image signal does not have the same bandwidth as an image having only the number of pixels of the 4: 1: 0 image signal. Can be reproduced while maintaining the same horizontal band characteristics as the 4: 2: 0 component format.

Further, according to the present invention, since the pixel replacement of the color difference signal is performed in the picture having the larger correlation between the frame correlation and the field correlation, the compression encoding efficiency can be improved. .

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a color difference signal pixel replacement method in first and second embodiments of the image compression encoding method of the present invention.

FIG. 2 is an explanatory diagram of a color difference signal pixel replacement method according to third and fourth embodiments of the image compression / encoding method of the present invention.

FIG. 3 is an explanatory diagram of a chrominance signal pixel replacement method in the first and second embodiments of the image compression / decoding method of the present invention.

FIG. 4 is an explanatory diagram of a color difference signal pixel replacement method in the third and fourth embodiments of the image compression / decoding method of the present invention.

FIG. 5 is a block diagram of a first embodiment of the compression encoding device of the present invention.

FIG. 6 is a block diagram of a first embodiment of the compression / decoding device of the present invention.

FIG. 7 is a block diagram of a compression encoding device according to a second embodiment of the present invention.

FIG. 8 is a block diagram of a third embodiment of the compression encoding device of the present invention.

FIG. 9 is a block diagram of a second embodiment of the compression / decoding device of the present invention.

FIG. 10 is a block diagram of a fourth embodiment of the compression encoding device of the present invention.

FIG. 11 is a block diagram of a third embodiment of the compression / decoding device of the present invention.

FIG. 12 is a table showing a part of an MPEG1 video stream picture layer.

FIG. 13 is a table showing a part of a system layer of an MPEG2 transport stream.

FIG. 14 is a diagram illustrating pixel positions of a luminance signal and a color difference signal of a 4: 2: 2 image signal, an MPEG2 image signal, an MPEG1 image signal, and a 4: 1: 1 image signal.

FIG. 15 is a block diagram illustrating an example of an MPEG encoder.

FIG. 16 is a block diagram illustrating an example of an MPEG decoder.

FIG. 17 shows a 4: 2: 2 image signal, a 4: 2: 0 image signal,
It is a conceptual diagram of each pixel number of a 4: 1: 1 image signal and a 4: 1: 0 image signal.

FIG. 18 is an explanatory diagram of determination of a frame correlation and a feed correlation.

FIG. 19 is a diagram illustrating a macroblock layer of MPEG2 video syntax.

[Explanation of symbols]

 41 chrominance signal 411/420 format converter 42 chrominance signal 411/420 pixel replacement unit 43 user interface 44,57 switch circuit (S / W) 45,64 MPEG encoder 46,74 buffer memory and formatter 47 synchronization control unit 48 Synchronization signal generator 49, 62 Identification code generator 50 Data recording unit 51 Recording medium 52 Buffer memory 53 Synchronization signal detector 54 Identification code detector 55, 68 MPEG decoder 56 Color difference signal generation method discriminator 58 Color difference signal 420 / 411 pixel replacement unit 59, 78 color difference signal output format converter 61 frame / field correlation determination unit 71 color difference signal 420/411 format converter 72 color difference signal 420/411 pixel replacement unit 73 DVC encoder 77 color difference signal 411 420 pixel replacing unit

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Claims (14)

[Claims] 1. A compression encoding method for compressing and encoding an image signal in a first component format and outputting the image signal, wherein a pixel position of a color difference signal in an input image signal in a second component format is determined by the first component format. Compression encoding of the input image signal after performing pixel replacement for replacing the pixel position with a pixel position equivalent to the pixel position of the color difference signal in the image signal. 2. A compression encoding method for compressing and encoding an image signal in a first component format and outputting the image signal, wherein a frame correlation or a field correlation is higher for each predetermined area of the input image signal in the second component format. When the frame correlation is higher, the pixel position of the color difference signal in the input image signal of the second component format is determined as the pixel position of the color difference signal of one frame in the image signal of the first component format. Pixel replacement is performed in a frame to be replaced with an equivalent pixel position, and when the field correlation is higher, the pixel position of the color difference signal in the input image signal of the second component format is replaced with the image signal of the first component format. Pixel position of color difference signal of each field in Compression encoding method, characterized in that after performing the replacement pixel in the field to replace the a pixel position, performs compression coding of the input image signal. 3. A compression encoding method for compressing and encoding an image signal in a first component format according to an MPEG system and outputting the image signal, wherein a frame correlation and a field correlation of a predetermined area of an input image signal of a second component format are provided. It is determined which is higher, and when the frame correlation is higher, the pixel position of the color difference signal in the input image signal of the second component format is changed to the pixel position of the color difference signal of one frame in the image signal of the first component format. Pixel replacement is performed in a frame to be replaced with a pixel position equivalent to the pixel position, and when the field correlation is higher, the pixel position of the color difference signal in the input image signal of the second component format is replaced with the first component format. Color difference of each field in the image signal After performing pixel replacement in a field to be replaced with a pixel position equivalent to the pixel position of the signal, the MPEG image compression is performed on the input image signal in accordance with the higher one of the frame correlation and the field correlation. A compression encoding method characterized by performing encoding. 4. The first component format is a 4: 2: 0 component format, the second component format is a 4: 1: 1 component format, and the input image signal is
4. The compression encoding method according to claim 1, wherein the compression encoding is performed in accordance with the EG method. 5. The first component format is a 4: 1: 1 component format, the second component format is a 4: 2: 0 component format, and the input image signal is a DV format.
4. The compression encoding method according to claim 1, wherein the compression encoding is performed in accordance with C. 6. The compression coding of the MPEG system is performed in accordance with the higher one of the frame correlation and the field correlation, and identification information indicating which correlation was used for the compression coding is transmitted to the MPEG system. 4. The compression encoding method according to claim 3, wherein the compression encoding method is shared with a specified motion compensation mode or DCT mode. 7. An encoding device for compressing and encoding an image signal in a first component format, wherein a pixel position of a color difference signal in an input image signal in a second component format is converted into an image signal in the first component format. A compression decoding method for performing a pixel replacement for replacing the pixel position with a pixel position equivalent to the pixel position of the middle chrominance signal, and then receiving a compression coded signal obtained by inputting and compressing and decoding the compressed coded signal in the first component format. Receiving the compressed and decoded signal, the pixel position of the color difference signal in the decoded signal of the first component format is the same as the pixel position of the color difference signal in the input image signal of the second component format. A compression decoding method characterized by performing pixel replacement for replacing a pixel position. 8. An encoding device for compressing and encoding an image signal in a first component format, comprising: determining which of a frame correlation and a field correlation is higher for each predetermined area of an input image signal of a second component format; When the frame correlation is higher, the pixel position of the color difference signal in the input image signal of the second component format is changed to a pixel equivalent to the pixel position of the color difference signal of one frame in the image signal of the first component format. Pixel replacement is performed in the frame to be replaced with the position, and when the field correlation is higher, the pixel position of the color difference signal in the input image signal of the second component format is replaced with each pixel position in the image signal of the first component format. Replace with pixel position equivalent to pixel position of field color difference signal The compression is performed by performing pixel replacement in a field to be obtained and input together with a compression-encoded signal obtained by input and identification information indicating which correlation has been used for compression-encoding, and performing compression-decoding in the first component format. In the decoding method, receiving the compressed decoded signal and the identification information, when it is determined that the input decoded signal was obtained by performing pixel replacement in a frame by the identification information, A pixel in a frame that replaces the pixel position of the color difference signal in the decoded signal of the first component format with a pixel position equivalent to the pixel position of the color difference signal of one frame in the image signal of the second component format When it is determined that the pixel is obtained by performing pixel replacement in the field, the first component Performing pixel replacement in a field for replacing the pixel position of the color difference signal in the decoded signal of the format with a pixel position equivalent to the pixel position of the color difference signal of one field in the image signal of the second component format. Characteristic compression / decoding method. 9. A compression encoding apparatus for compressing and encoding an image signal in a first component format and outputting the image signal, wherein a pixel position of a color difference signal in an input image signal in a second component format is determined by the first component format. A pixel replacement unit that replaces the pixel position of the color difference signal in the image signal with a pixel position equivalent to the pixel position of the color image signal; an encoder that compresses and codes an output image signal of the pixel replacement unit in the first component format; Multiplexing means for multiplexing and outputting an identification code indicating that the pixel replacement has been performed in the output coded signal of the device. 10. A compression encoding apparatus for compressing and encoding an image signal in a first component format and outputting the image signal, wherein which of a frame correlation and a field correlation is higher for each predetermined area of an input image signal of a second component format A determining unit that determines a pixel position of a color difference signal in an input image signal of the second component format when the frame correlation is higher based on a determination result of the correlation determining unit; Pixel replacement in a frame to be replaced with a pixel position equivalent to the pixel position of the color difference signal of one frame in the image signal is performed. When the field correlation is higher, the color difference signal in the input image signal of the second component format is used. The pixel position of the first component format A pixel replacement unit that performs pixel replacement in a field to be replaced with a pixel position equivalent to a pixel position of a color difference signal of each field in an image signal; and a compression code of an output image signal of the pixel replacement unit in the first component format. And a multiplexing means for multiplexing and outputting an identification code indicating that the pixel replacement has been performed in an output coded signal of the coder and outputting the coded signal. . 11. The encoder performs compression encoding based on the MPEG system, and, based on a determination result of the correlation determination unit, determines which one of the frame correlation and the field correlation is higher for the input image signal. M according to the correlation of
11. The compression encoding apparatus according to claim 10, wherein the compression encoding is performed by PEG. 12. An encoding device for compressing and encoding an image signal in a first component format, wherein a pixel position of a color difference signal in an input image signal of a second component format is converted into an image signal of the first component format. A decoder that receives a compression-encoded signal obtained by inputting after performing pixel replacement for replacing the pixel position with a pixel position equivalent to the pixel position of the color difference signal therein, and compression-decodes in the first component format; Upon receiving the output decoded signal of the decoder, the pixel position of the color difference signal in the decoded signal of the first component format is shifted to the same pixel position as the pixel position of the color difference signal in the input image signal of the second component format. A pixel replacement unit that outputs the same image signal as the image signal input to the encoding device. Compression decoding apparatus according to claim Rukoto. 13. An encoding apparatus for compressing and encoding an image signal in a first component format, comprising: determining which of a frame correlation and a field correlation is higher for each predetermined area of an input image signal of a second component format; When the frame correlation is higher, the pixel position of the color difference signal in the input image signal of the second component format is changed to a pixel equivalent to the pixel position of the color difference signal of one frame in the image signal of the first component format. Pixel replacement is performed in the frame to be replaced with the position, and when the field correlation is higher, the pixel position of the color difference signal in the input image signal of the second component format is replaced with each pixel position in the image signal of the first component format. Place it at a pixel position equivalent to the pixel position of the color difference signal of the field The compression is performed by performing pixel replacement in a field to be replaced and receiving together with a compression-encoded signal obtained by input and identification information indicating which correlation has been used for compression-encoding, and performing compression-decoding in the first component format. A decoder for decoding; receiving an output decoded signal of the decoder and the identification information;
When it is determined that the input decoded signal is obtained by performing pixel replacement in a frame by the identification information,
A pixel in a frame that replaces the pixel position of the color difference signal in the decoded signal of the first component format with a pixel position equivalent to the pixel position of the color difference signal of one frame in the image signal of the second component format When it is determined that the color difference signal is obtained by performing the pixel replacement in the field and performing the pixel replacement in the field, the pixel position of the color difference signal in the decoded signal of the first component format is determined as follows:
A pixel replacement unit that performs pixel replacement in a field to be replaced with a pixel position equivalent to a pixel position of a color difference signal of one field in the image signal of the second component format. . 14. The decoder performs compression decoding based on the MPEG system, and, based on the identification information, correlates the input compression-coded signal with a higher one of the frame correlation and the field correlation. According to the MPEG
14. The compression decoding apparatus according to claim 13, wherein the compression decoding is performed in a system.