JPH09200755A - Orthogonal transformation encoder and decoder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the high-efficiency encoding of high-quality still picture without changing the system of high-efficiency encoding for a moving image so much by dividing the same still picture into plural kinds of picture element blocks. SOLUTION: An image signal inputted from an input terminal IN is blocked without shifting any picture element, blocked while being shifted just for the prescribed number of picture elements, and supplied to a switching means 106 as the signal of 8×8 picture elements respectively blocked by respective blocking means 101-105. The switching means 106 selects any supplied blocked signal and supplies it to an orthogonal transforming means 107 for each signal of 8×8 picture elements. The orthogonal transforming means 107 performs two-dimensional discrete cosine transformation to the blocked signal of 8×8 picture elements and outputs the result to an output terminal OUT. Since the positions of plural kinds of still pictures are matched and averaged, distortion at the boundary of respective picture element blocks can be reduced and the high- quality still picture can be provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an orthogonal transform coding device and a decoding device, and for example, an orthogonal transform coding / decoding used for high efficiency coding of a signal having a large amount of data such as a video signal. It is suitable for use in an apparatus.

[0002]

2. Description of the Related Art In recent years, due to the progress of digital signal processing technology, a large amount of digital information such as a moving image signal, a still image signal, a voice signal, etc. is highly efficiently encoded and recorded on a small magnetic medium or a communication medium. It is possible to transmit to.

Conventionally, a method using orthogonal transform coding such as discrete cosine transform or Hadamard transform has been known as high-efficiency coding of image signals and audio signals. FIG.
It is a block diagram which shows the conventional structural example of an orthogonal transformation encoding device. In FIG. 5, 301 is an input terminal, 302 is a blocking means, 303 is an orthogonal transformation means, and 304 is an output terminal. The input signal supplied to the input terminal 301 is
In the blocking means 302, the pixel blocks are divided into 8 horizontal blocks and 8 vertical blocks, that is, a total of 64 pixel blocks.

FIG. 6 is a diagram showing a conventional example of blocking for an image signal composed of 128 pixels × 64 pixels. In FIG. 6, the image signal is divided into pixel blocks of 8 × 8 pixels from the left end without any gap.

The orthogonal transformation means 303 performs a two-dimensional discrete cosine transformation on the pixel block obtained by the blocking means 302 and supplies it to the output terminal 304. Output terminal 30
Generally, the orthogonal transform code supplied to 4 is highly efficient coded by the quantizing means and the variable length coding means.

[0006]

When high-efficiency coding of an image or audio is performed using the above-described conventional orthogonal transform coding apparatus, distortion occurs at the boundary between pixel blocks and the image and There is a problem in that the quality of voice tends to deteriorate.

In particular, there is a drawback that deterioration of an edge portion or a flat portion in a still image is conspicuous. Therefore, in order to obtain a high quality still image, a method of setting the compression rate of the still image lower than that of the moving image and performing quantization and variable length coding has been conventionally considered.

However, in the method of setting the compression ratio of the still image lower than the compression ratio of the moving image, when handling both the moving image and the still image, a circuit corresponding to each of them is required. There was a problem that the circuit scale became large.

In view of the above problems, it is an object of the present invention to enable high-quality still image high-efficiency encoding without significantly changing the high-efficiency encoding method for moving images. And

[0010]

An orthogonal transform coding apparatus according to the present invention comprises a first blocking means for blocking a pixel of an input image signal into a block of a predetermined number of pixels without shifting, and Pixel shift blocking means for shifting the pixels of the input image signal by a predetermined number of pixels to form blocks of a predetermined number of pixels, and orthogonal transformation of the pixel blocks blocked by the respective blocking means. And orthogonal transformation means for performing the same.

Another feature of the present invention is that
The present invention is characterized in that the input image signal is divided into blocks using the plurality of types of blocking means to generate and output a plurality of types of orthogonal transform codes for the same input signal sequence.

Another feature of the present invention is that the pixel shift blocking means shifts the input signal sequence in the horizontal direction by an integer of m and then blocks the input signal sequence.

Another feature of the present invention is that the pixel shift blocking means shifts the two-dimensional input signal sequence by an integer number m in the horizontal direction and an integer number n in the vertical direction. It is characterized by blocking later.

Another feature of the present invention is a first blocking means for blocking the pixels of an input image signal into blocks of a predetermined number of pixels without shifting the pixels, and the above-mentioned input. Second blocking means for shifting the image signal to the right by a predetermined number of pixels to form a block of a predetermined number of pixels, and shifting the input image signal to the left by a predetermined number of pixels. A third blocking means for blocking into a block of a predetermined number of pixels, and a third blocking means for shifting the input image signal downward by a predetermined number of pixels into a block of a predetermined number of pixels. 4, blocking means for shifting the input image signal in the upward direction by a predetermined number of pixels to block into blocks of a predetermined number of pixels, and the first to fifth blocking means. Nobu It is characterized by having a orthogonal transform means for orthogonally converting the pixel blocks blocked, respectively, by click means.

Another feature of the present invention is that the signal blocked by the first blocking means is always selected when a moving image signal is input.

Further, the orthogonal transform decoding apparatus of the present invention comprises an inverse orthogonal transform means for performing an inverse orthogonal transform on an orthogonal transform code which has been blocked by a plurality of types of blocking means and which has been encoded, and the inverse orthogonal transform means. And a synthesizing unit for synthesizing a plurality of signal sequences inversely orthogonally transformed by the transforming unit into one signal sequence.

Another feature of the present invention is that
The above-mentioned synthesizing means is characterized by sequentially outputting the supplied image signals in decoding the moving image signals.

Another feature of the present invention is that the above-mentioned synthesizing means synthesizes a single still image from image signals supplied over a plurality of frames in decoding the still image signal. It is characterized by outputting.

[0019]

Since the present invention comprises the above-mentioned technical means, according to the orthogonal transform coding apparatus of the present invention, the pixels are divided into blocks without shifting, and the pixels are shifted by a predetermined number of pixels to form blocks. . As a result, the same still image is divided into a plurality of types of pixel blocks, and each pixel block is orthogonally transformed, and a plurality of types of orthogonal transformation codes are generated and output. Further, according to the orthogonal transform decoding device of the present invention, a plurality of types of still images decoded from the plurality of types of orthogonal transform codes are combined into one image.

Therefore, in the orthogonal transform encoding device and the decoding device of the present invention, when the moving image is subjected to the orthogonal transform encoding process, the first image forming means blocks the input image signal. Since it is possible to form a block of a predetermined number of pixels without shifting the pixels of, the processing can be performed in exactly the same manner as the conventional high efficiency encoding.

Further, when the still image is subjected to the orthogonal transform coding process, the pixel shift blocking means performs the orthogonal transform coding process by blocking the pixel so that the pixels of the inputted image signal are predetermined. Orthogonal transformation can be performed after shifting by a number of pixels to form blocks. Therefore, when synthesizing the still images, if the image signals of a plurality of frames are aligned and averaged, the distortion of the boundary of each pixel block can be reduced, and high-quality still image decoding can be performed. You will be able to do it.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION The orthogonal transform coding apparatus and decoding apparatus of the present invention will be described below more specifically with reference to the drawings. FIG. 1 is a block diagram showing a configuration example of an orthogonal transform coding device according to the present invention. In FIG.
Is an image signal input terminal, and in the present embodiment, 128
An image signal composed of x64 pixels is input.

Reference numerals 101 to 105 denote first to fifth blocking means for dividing the image signal input from the input terminal IN into pixel blocks of 8 × 8 pixels, and the blocking means 101 to 105 respectively. The blocked 8 × 8 pixel signal is supplied to the switching unit 106.

The switching means 106 selects the blocked signals supplied from the blocking means 101 to 105 and supplies them to the orthogonal transformation means 107 for each 8 × 8 pixel signal. The orthogonal transform means 107 performs a two-dimensional discrete cosine transform on the block signal of 8 × 8 pixels supplied from the switch means 106 and outputs it to the output terminal OUT.

2 (a)-(c) and 3 (a)-
(B) is the first to fifth blocking means 101 to 1
It is a figure which shows the example of 5 types of blocking processing in 05. FIG. 2A shows 8 × without a gap from the upper left end of the image signal.
This is a conventional block forming process in which blocks are formed every 8 pixels, and when the moving image signal is input, the switching means 1 is used.
06 always selects the first blocking means 102 that performs this blocking processing. With the above blocks and the orthogonal transform processing, the orthogonal transform coding apparatus of the present embodiment can process a moving image completely equivalent to conventional high-efficiency coding such as a digital VTR.

2B to 2C, the image signal is shifted to the right and left by two pixels respectively, and in FIGS. 3A and 3B, the image signal is shifted to the lower and upper by two pixels, respectively. When the still image signal is input, the switching unit 106 sequentially selects the blocking units 101 to 105 over 5 frames. That is, when the orthogonal transform coding apparatus according to the present embodiment is applied to a digital VTR, an image of 5 frames shifted by 2 pixels from a single still image is recorded on the magnetic medium.

Next, an orthogonal transform decoding device for decoding the signal orthogonally transformed by the orthogonal transform coding device of this embodiment will be described. FIG. 4 is a block diagram showing a configuration example of the orthogonal transform decoding device according to the present embodiment. In FIG. 4, the orthogonal transform code input to the input terminal 201 is subjected to two-dimensional inverse discrete cosine transform by the orthogonal transform means 202, decoded into an image signal, and supplied to the switching means 203.

The switching means 203 switches the image signal decoded by the inverse orthogonal transformation means 202 for each frame and outputs it. When decoding the moving image signal, the combining unit 204 sequentially outputs the supplied image signals to the output terminal 205.

Further, when decoding the still image signal, the synthesizing means 204 synthesizes a single still image from the image signals supplied for 5 frames and shifted by 2 pixels, and synthesizes the still image. The generated image signal is output to the output terminal 205.

The image signals of 5 frames which are shifted by the amount of 2 pixels described above include pixel block boundary distortions at different positions because the pixel block boundaries are different. Therefore, by aligning and averaging the positions of the image signals of these five frames, it is possible to reduce the distortion at the pixel block boundary and synthesize a high quality image.

[0031]

As described above, according to the orthogonal transform coding apparatus of the present invention, the pixels are divided into blocks without being shifted, and a predetermined number of pixels are shifted to form blocks. Therefore, the same still image can be divided into a plurality of types of pixel blocks, and a plurality of types of orthogonal transform codes can be generated and output by orthogonally transforming each pixel block.

Further, according to the orthogonal transform decoding apparatus of the present invention, a plurality of types of still images can be synthesized into one still image by decoding and synthesizing the plurality of types of orthogonal transform codes.

Therefore, when combining the plurality of types of still images into one still image, the plurality of types of still images are aligned and averaged to reduce the distortion at the boundary of each pixel block. Therefore, a high quality still image can be obtained. Thus, according to the present invention,
Distortion at the boundary between pixel blocks can be reduced without significantly changing the high-efficiency encoding method for moving images, and high-quality still image encoding and decoding can be performed.

[Brief description of drawings]

FIG. 1 is a block diagram showing an example of the configuration of an orthogonal transform coding device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a specific block forming process of a block forming unit in FIG.

FIG. 3 is a diagram showing a specific block forming process of a block forming unit in FIG.

FIG. 4 is a block diagram showing a configuration example of an orthogonal transform decoding device of the present invention.

FIG. 5 is a block diagram showing a configuration example of a conventional orthogonal transform encoding device.

FIG. 6 is a diagram showing a specific block process of a blocking unit in FIG.

[Explanation of symbols]

 IN input terminal 101 first blocking means 102 second blocking means 103 third blocking means 104 fourth blocking means 105 fifth blocking means 106 switching means 107 orthogonal transformation means OUT output terminal 201 input Terminal 202 Inverse Orthogonal Transforming Means 203 Switching Means 204 Combining Means 205 Output Terminals 301 Input Terminals 302 Blocking Means 303 Orthogonal Transforming Means 304 Output Terminals

Claims (9)

[Claims] 1. A first block for dividing a pixel of an input image signal into a block of a predetermined number of pixels without shifting.
Blocking means, a pixel shift blocking means for shifting the pixels of the input image signal by a predetermined number of pixels to form a block of a predetermined number of pixels, and each of the blocking means for blocking. And an orthogonal transform means for orthogonally transforming the selected pixel block. 2. A plurality of types of orthogonal transform codes are generated and output for the same input signal sequence by dividing the input image signal into blocks using the plurality of types of blocking means. The orthogonal transform encoding device according to claim 1. 3. The orthogonal according to claim 1, wherein the pixel shift blocking means shifts the input signal sequence by an integer m in the horizontal direction and then blocks the input signal sequence. Transform coding device. 4. The pixel shift blocking means shifts the two-dimensional input signal sequence horizontally by an integer of m, and vertically shifts by an integer of n, and then blocks. The orthogonal transform encoding device according to any one of Items 1 to 3. 5. A first block for dividing a pixel of an input image signal into a block of a predetermined number of pixels without shifting.
Blocking means, second blocking means for shifting the input image signal to the right by a predetermined number of pixels to form a block of a predetermined number of pixels, and the input image signal Third blocking means for shifting a predetermined number of pixels to the left to form a block of a predetermined number of pixels; and a predetermined number of pixels for shifting the input image signal downward. Fourth blocking means for blocking into blocks of a number of pixels, and fifth block for shifting the input image signal upward by a predetermined number of pixels into blocks of a predetermined number of pixels. An orthogonal transform encoding device, comprising: an encoding unit and an orthogonal transform unit that orthogonally transforms the pixel blocks divided into blocks by the first to fifth blocking units. 6. The orthogonal transform coding apparatus according to claim 5, wherein the signal blocked by the first blocking means is always selected when a moving image signal is input. 7. An inverse orthogonal transform means for performing an inverse orthogonal transform on an orthogonal transform code which has been blocked using a plurality of types of blocking means and has been encoded, and a plurality of inverse orthogonal transforms performed by the inverse orthogonal transform means. An orthogonal transform decoding device, comprising: a synthesizing unit that synthesizes a signal sequence into one signal sequence. 8. The orthogonal transform decoding apparatus according to claim 7, wherein said synthesizing means sequentially outputs the supplied image signals in decoding the moving image signals. 9. The decoding means for synthesizing a still image signal, wherein said synthesizing means synthesizes and outputs a single still image from image signals supplied over a plurality of frames. The described orthogonal transform decoding device.