IMAGE DECODING APPARATUS, IMAGE ENCODING APPARATUS, AND METHOD AND PROGRAM FOR IMAGE DECODING AND ENCODING

• US 20150281697A1
• Filed: 05/22/2015
• Published: 10/01/2015
• Est. Priority Date: 06/09/2010
• Status: Active Grant

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: KONDO, Kenji
• Granted Patent: US 9,596,476 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06T 9/004 Predictors, e.g. intraframe, interframe coding
• CPC Class Codes: G06T 9/007 Transform coding, e.g. discrete cosine transform
• CPC Class Codes: H04N 19/103 Selection of coding mode or of prediction mode
• CPC Class Codes: H04N 19/11 among a plurality of spatial predictive coding modes
• CPC Class Codes: H04N 19/122 Selection of transform size, e.g. 8x8 or 2x4x8 DCT; Selection of sub-band transforms of varying structure or type
• CPC Class Codes: H04N 19/124 Quantisation
• CPC Class Codes: H04N 19/136 Incoming video signal characteristics or properties
• CPC Class Codes: H04N 19/14 Coding unit complexity, e.g. amount of activity or edge presence estimation H04N19/146 takes precedence
• CPC Class Codes: H04N 19/176 the region being a block, e.g. a macroblock
• CPC Class Codes: H04N 19/184 the unit being bits, e.g. of the compressed video stream
• CPC Class Codes: H04N 19/197 including determination of the initial value of an encoding parameter H04N19/56 takes precedence
• CPC Class Codes: H04N 19/44 Decoders specially adapted therefor, e.g. video decoders which are asymmetric with respect to the encoder
• CPC Class Codes: H04N 19/46 Embedding additional information in the video signal during the compression process H04N19/517, H04N19/68, H04N19/70 take precedence
• CPC Class Codes: H04N 19/61 in combination with predictive coding

Abstract

An encoded bit stream is processed by a lossless decoding unit (52), an inverse quantization unit (53), and an inverse orthogonal transform unit (54) in this order, to obtain orthogonally transformed coefficient data and encoding parameter information. The inverse orthogonal transform unit (54) performs an inverse orthogonal transform on the coefficient data by using bases that are set beforehand in accordance with the locations of transform blocks in a macroblock indicated by the encoding parameter information. In this manner, prediction error data is obtained. An intra prediction unit (62) generates predicted image data. An addition unit (55) adds the predicted image data to the prediction error data, to decode image data. By using bases that are set in accordance with the locations of transform blocks, an optimum inverse orthogonal transform can be performed, and encoding efficiency can be increased.

Claims

1-16. -16. (canceled)

17. An image decoding apparatus that performs an orthogonal transform on prediction error data of each transform block, and decodes image data from an encoded bit stream generated by processing coefficient data subjected to the orthogonal transform, the prediction error data being a difference between the image data and predicted image data, the image decoding apparatus comprising:

a data processing unit configured to process the encoded bit stream to obtain the coefficient data subjected to the orthogonal transform and encoding parameter information;

a selector to determine an inverse orthogonal transform procedure based on a size of a transform block and a prediction mode;

an inverse orthogonal transform unit configured to perform the determined inverse orthogonal transform procedure on the coefficient data by using a base to obtain the prediction error data, the base being set beforehand in accordance with a location of the transform block in a macroblock indicated by the encoding parameter information;

a predicted image data generation unit configured to generate the predicted image data; and

an addition unit configured to add the predicted image data generated by the predicted image data generation unit to the prediction error data obtained by the inverse orthogonal transform unit, to decode the image data.

18. The image decoding apparatus according to claim 17, wherein the inverse orthogonal transform unit performs the inverse orthogonal transform by using a base set beforehand in accordance with the location of the transform block and a prediction mode indicated by the encoding parameter information.

19. The image decoding apparatus according to claim 18, wherein, when the encoding parameter information indicates that the macroblock contains a plurality of transform blocks, the inverse orthogonal transform unit performs the inverse orthogonal transform by using a base on orthogonally transformed coefficient data of the lowest-frequency component coefficient data after an orthogonal transform of the respective transform blocks contained in the macroblock, the base being set beforehand in accordance with the prediction mode.

20. The image decoding apparatus according to claim 18, wherein the base used by the inverse orthogonal transform unit is an inverse matrix of a base used in the orthogonal transform of the prediction error data of each transform block.

21. The image decoding apparatus according to claim 17, wherein the inverse orthogonal transform unit performs a Karhunen-Loeve inverse transform using the base.

22. An image decoding method for performing an orthogonal transform on prediction error data of each transform block, and decoding image data from an encoded bit stream generated by processing coefficient data subjected to the orthogonal transform, the prediction error data being a difference between the image data and predicted image data, the image decoding method comprising the steps of:

processing the encoded bit stream to obtain the coefficient data subjected to the orthogonal transform and encoding parameter information;

determine an inverse orthogonal transform procedure based on a size of a transform block and a prediction mode;

performing the determined inverse orthogonal transform procedure on the coefficient data by using a base to obtain the prediction error, the base being set beforehand in accordance with a location of the transform block in a macroblock indicated by the encoding parameter information;

generating the predicted image data; and

adding the generated predicted image data to the prediction error obtained by the inverse orthogonal transform unit, to decode the image data.

23. A non-transitory computer-medium storing a program for causing a computer to perform an orthogonal transform on prediction error data of each transform block, and decode image data from an encoded bit stream generated by processing coefficient data subjected to the orthogonal transform, the prediction error data being a difference between the image data and predicted image data, the program causing the computer to:

process the encoded bit stream to obtain the coefficient data subjected to the orthogonal transform and encoding parameter information;

determine an inverse orthogonal transform procedure based on a size of a transform block and a prediction mode;

perform the determined inverse orthogonal transform procedure on the coefficient data by using a base to obtain the prediction error, the base being set beforehand in accordance with a location of the transform block in a macroblock indicated by the encoding parameter information;

generate the predicted image data; and

add the generated predicted image data to the prediction error obtained by the inverse orthogonal transform unit, to decode the image data.

24. An image encoding apparatus that encodes image data, the image encoding apparatus comprising:

a prediction unit configured to generate predicted image data of the image data;

a subtraction unit configured to generate prediction error data, the prediction error data being a difference between the image data and the predicted image data;

a selector to determine an orthogonal transform procedure based on a size of a transform block and a prediction mode;

an orthogonal transform unit configured to perform the determined orthogonal transform procedure on the prediction error of each transform block by using a base set beforehand in accordance with a location of the transform block in a macroblock; and

a data processing unit configured to process data output from the orthogonal transform unit, to generate an encoded bit stream.

25. The image encoding apparatus according to claim 24, wherein the orthogonal transform unit performs the orthogonal transform by using a base set beforehand in accordance with the location of the transform block and a prediction mode used when the prediction unit generates the predicted image data.

26. The image encoding apparatus according to claim 25, wherein, when the macroblock contains a plurality of transform blocks, the orthogonal transform unit performs an orthogonal transform by using a base, the orthogonal transform being performed on a block using the lowest-frequency component coefficient among the respective transform blocks subjected to the orthogonal transform in the macroblock, the base being set beforehand in accordance with the prediction mode.

27. The image encoding apparatus according to claim 25, wherein the base used by the orthogonal transform unit is eigenvectors corresponding to eigenvalues of a matrix calculated from a size of the macroblock, a size of the transform block, locations of the transform blocks in the macroblock, and predicted error data in each transform block in each prediction mode.

28. The image encoding apparatus according to claim 27, wherein the base used by the orthogonal transform unit is grouped in accordance with a distance between bases.

29. The image encoding apparatus according to claim 27, wherein the base used by the orthogonal transform unit is grouped in accordance with a distance from a reference pixel.

30. The image encoding apparatus according to claim 24, wherein the orthogonal transform unit performs a Karhunen-Loeve transform by using the base.

31. An image encoding method for encoding image data, the image encoding method comprising the steps of:

generating predicted image data of the image data;

generating prediction error data, the prediction error data being a difference between the image data and the predicted image data;

determining an orthogonal transform procedure based on a size of a transform block and a prediction mode; and

performing the determined orthogonal transform procedure on the prediction error of each transform block by using a base set beforehand in accordance with a location of the transform block in a macroblock.

32. A non-transitory computer-medium storing a program for causing a computer to encode image data, the program causing the computer to:

generate predicted image data of the image data;

generate prediction error data, the prediction error data being a difference between the image data and the predicted image data;

determine an orthogonal transform procedure based on a size of a transform block and a prediction mode; and

perform the determined orthogonal transform procedure on the prediction error of each transform block by using a base set beforehand in accordance with a location of the transform block in a macroblock.