JPH06177774A - Method and device for reproducing pictures - Google Patents

Abstract

PURPOSE:To simply exchange the scanning order of two-step scanning and to reduce the load of hardware by performing a two dimensional code scanning in the order of scanning in reverse orthogonal transformation. CONSTITUTION:When a zigzag scanning is restored in a code allocation decoding section 5, the data input order of 1 2 3 ... 15 16 is changed to the order of that the scanning of the two dimensional code is performed in the order of scanning in the reverse orthogonal transformation by one processing as 1 7 2 6 10 16 11 15 3 13 5 8 4 14 9 12 by taking the arithmetic order change of a high-speed arithmetic algorithm in an information extraction decoding section 9 into account. Thus, the two blocks of buffers are conventionally required for the double intra-block order change but now one block of buffer can perform the processing of order change executed in two steps before once. Accordingly, the capacity of buffer memory to be used for the scanning order change can be halved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reproducing method and an image reproducing apparatus for efficiently decoding an image signal compressed by high efficiency coding to reproduce an image.

[0002]

2. Description of the Related Art A typical configuration of an information source decoder for decompressing compressed image information is, for example, as shown in FIG. 1, an entropy decoding unit 1 and a FIFO (fast in fast
Out) buffer 3, code assignment decoding unit 5, dequantization unit 7
And an information extraction / decoding unit 9. The entropy decoding unit 1 decodes the entropy code (Huffman code, run length code, etc.) of the input variable length compressed image data into a two-dimensional code before entropy coding. The FIFO buffer 3 is a memory for matching the asynchronous operation of the entropy decoding unit 1 with the synchronous operation of the code assignment decoding unit 5, the dequantization unit 7, and the information extraction decoding unit 9. The code assignment decoding unit 5 obtains quantized coefficient data by two-dimensional code decoding processing, intra-block scan order conversion, and the like. The inverse quantization unit 7 transforms this quantized coefficient data by inverse quantization to realize nonlinear quantized data. The information extraction / decoding unit 9 obtains actual image data by performing inverse orthogonal transformation such as prediction code decoding processing and Hadamard transformation processing.

Of the above, the code assignment decoding unit 5 performs zigzag scanning for each block and decodes a code (two-dimensional event) in which a zero run length and a non-zero coefficient are combined. It is necessary to convert the zigzag scan for scanning the orthogonal transform coefficient in 9 from the low frequency component to the high frequency component in the scan direction of the normal two-dimensional matrix in the block.

The information extraction / decoding unit 9 generally uses orthogonal transform in many cases, and the orthogonal transform coefficients arranged in order from the low-frequency component to the high-frequency component are arranged in order. A special intra-block scan order is used to match This scanning order changes according to the content (type) of the high speed operation algorithm, and there are various patterns.

This will be described in detail with an example of a 4 × 4 block. In the conventional information source decoder, 4 × 4 = 16.
The input data order of (pixel) is 1 → 2 → 3 → 4 → 5 → 6 → 7 → 8 → 9 → 10 → 11 → 1
2 → 13 → 14 → 15 → 16, first, the zigzag scanning is restored in the code allocation decoding unit 5, and as shown in FIG. 2A, 1 → 2 → 6 → 7 → 3 → 5 → 8 → 13 → 4 → 9 → 12 → 1
4 → 10 → 11 → 15 → 16, and further, in the information extraction / decoding unit 9, the data is converted into the operation order of the high speed operation algorithm, and the above data order is changed to 1 → 7 → as shown in FIG. 2 → 6 → 10 → 16 → 11 → 15 → 3 → 13 →
5 → 8 → 4 → 14 → 9 → 12.

[0006]

As described above, in the conventional apparatus as described above, the scanning order conversion is performed in units of one block in each of the two functional blocks of the code assignment decoding unit and the information extraction decoding unit. ing. In order to perform the scan order conversion within one block, it is necessary to buffer the data for one block. Therefore, in order to perform the scan order conversion within one block twice as in the conventional case, a buffer for two blocks must be used. Requires memory.

Therefore, in the prior art, the load on the hardware is considerably heavy due to the necessity of performing the scanning order conversion twice, and it is not preferable in terms of processing speed.

In view of the above points, an object of the present invention is to provide an image reproducing method and an image reproducing apparatus of a scanning order conversion system which can simplify the scanning order conversion twice and reduce the load of hardware. It is in.

[0009]

To achieve the above object, the present invention provides an image reproducing method for reproducing an image by decoding a variable length code into a two-dimensional code and further performing an inverse orthogonal transform. The scanning of the dimensional code is performed in the scanning order in the inverse orthogonal transform.

Further, according to the present invention, in an image reproducing apparatus for reproducing an image by decoding a variable length code into a two-dimensional code and further performing an inverse orthogonal transformation, the scanning of the two-dimensional code is performed in the inverse orthogonal transformation. It is characterized in that it has a decoding means for performing in order.

Further, according to the present invention, in an image reproducing apparatus for reproducing an image by decoding a variable-length code into a two-dimensional code, performing inverse quantization, and further performing inverse orthogonal transformation, the inverse quantization table is used for the inverse quantization table. It can be characterized in that it has means for forming in a scanning order of orthogonal transformation.

[0012]

According to the present invention, the zigzag scan / raster scan conversion in the code allocation decoding unit in the information source decoder and the order conversion for high speed Hadamard conversion in the information extraction decoding unit are performed according to the present invention.
The code allocation decoding unit collectively performs the processing at once. That is, the scanning of the two-dimensional code is performed in the scanning order in the inverse orthogonal transform. As described above, in the present invention, the conventional intra-block scanning order conversion is performed twice, so that the required buffer memory capacity can be reduced, the hardware can be reduced, and the processing time can be shortened.

[0013]

Embodiments of the present invention will now be described in detail with reference to the drawings.

The schematic structure of the information source decoder used in the embodiment of the present invention is almost the same as that shown in FIG. 1, and the detailed description thereof is omitted. However, in the embodiment of the present invention, the scan order conversion, which has conventionally been performed separately in the two functional blocks of the code assignment decoding unit 5 and the information extraction decoding unit 9, is performed once in the code assignment decoding unit 5 as described below. Will be done together.

That is, when the zigzag scanning is restored in the code allocation decoding unit 5, the operation order conversion of the high speed operation algorithm in the information extraction decoding unit 9 is also taken into consideration, and 1 → 2 → 3 → 4 → 5 → 6 → 7. → 8 → 9 → 10 → 11 → 1
The data input order of 2 → 13 → 14 → 15 → 16 at once is as shown in (A) of FIG. 3 ((B) of FIG. 3 shows only the order of (A) by an arrow line). 1 → 7 → 2 → 6 → 10 → 16 → 11 → 15 → 3 → 13 →
Converted as 5 → 8 → 4 → 14 → 9 → 12. That is, the scanning of the two-dimensional code is performed in the scanning order in the inverse orthogonal transform.

As a result, a buffer for two blocks is conventionally required for two intra-block order conversions as shown in FIG. 2 described above, but a buffer for one block is actually used for two times. The order conversion can be done at once. Since the dequantization unit 7 between the code assignment decoding unit 5 and the information extraction decoding unit 9 is an independent operation for each data, the operation order of the data can be freely set, and the operation order is hardware. It does not affect the wear load.

Therefore, according to the embodiment of the present invention, the capacity of the buffer memory used for the scanning order conversion can be reduced by half, and the load of the hardware for realizing the order conversion can be reduced, and the processing speed can be reduced. It also contributes to speeding up.

Note that the present invention is not limited to the above-mentioned FIG. 3, and the scanning order thereof can be changed according to the contents of the high speed operation algorithm, and various patterns can be applied.

The same effect can be obtained by forming the inverse quantization table in the inverse quantization section 7 in the scanning order of the inverse orthogonal transform.

[0020]

As described above, according to the present invention,
Since the scanning order conversion processing which has conventionally been performed twice is collectively performed at one time, that is, the scanning of the two-dimensional code is performed in the scanning order in the inverse orthogonal conversion, the capacity of the buffer memory can be halved. In addition, the load of the hardware for realizing the order conversion is reduced, and the processing speed is improved.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of an information source decoder of an image reproducing device to which the present invention can be applied.

FIG. 2 is a diagram showing a conventional scan order conversion system.

FIG. 3 is a diagram showing a scanning order conversion system according to an embodiment of the present invention.

[Explanation of symbols]

 1 Entropy Decoding Unit 3 FIFO Buffer 5 Code Assignment Decoding Unit 7 Inverse Quantization Unit 9 Information Extraction Decoding Unit

Claims (3)

[Claims] 1. An image reproducing method for reproducing an image by decoding a variable length code into a two-dimensional code and further performing an inverse orthogonal transform, wherein scanning of the two-dimensional code is performed in a scanning order in the inverse orthogonal transform. Image reproduction method characterized by. 2. An image reproducing apparatus for reproducing an image by decoding a variable-length code into a two-dimensional code and further performing an inverse orthogonal transform, wherein the two-dimensional code is scanned in a scanning order in the inverse orthogonal transform. An image reproducing apparatus comprising means. 3. An image reproducing apparatus for reproducing an image by decoding a variable-length code into a two-dimensional code, performing inverse quantization and then performing inverse orthogonal transformation, and scanning an inverse quantization table for the inverse orthogonal transformation. An image reproducing apparatus having means for forming in order.