A video encoding apparatus includes an intra prediction error collector; a transform base generator; an intra predictor; and a transform encoder, the intra prediction error collector collecting prediction errors of blocks having an equal intra prediction mode from macroblocks in a regular unit, which are encoded prior to a current macroblock, the transform base generator generating transform bases for respective intra prediction modes based on the prediction errors collected by the intra prediction error collector. Accordingly, the intra prediction encoding performance can be significantly improved with adding no addition information by adaptively generating a transform base according to an image characteristic change and transform-encoding an intra prediction error. As a result, the compression efficiency of a video compression apparatus or the picture quality of a reconstructed image can be greatly improved.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A video encoding apparatus, comprising: an intra prediction error collector configured to collect, for an intra prediction mode of a current block, prediction errors of respective blocks having the same intra prediction mode as the intra prediction mode of the current block, the respective blocks being encoded prior to encoding the current block; a transform base generator configured to generate a transform base for the intra prediction mode based on the collected prediction errors; an intra predictor configured to predict the current block to generate a predicted block by using neighboring pixels of the current block according to the intra prediction mode of the current block, and generate a prediction error block of the current block according to a difference between the predicted block and the current block; and a transform encoder configured to transform the prediction error block by using the transform base for the intra prediction mode, wherein the transform base generator comprises a correlation matrix calculator configured to calculate an autocorrelation matrix for the intra prediction mode by using (i) each first matrix corresponding to each of the collected prediction errors of each of the respective blocks for the intra prediction mode and (ii) each transpose matrix of said each first matrix, wherein the autocorrelation matrix for the intra prediction mode is generated based on an average of respective multiplications of said each first matrix and said each transpose matrix of said each first matrix, and wherein the transform base for the intra prediction mode is generated based on the autocorrelation matrix for the intra prediction mode.
2. The video encoding apparatus of claim 1 , wherein the transform base generator further comprises: an eigenvector calculator configured to calculate an eigenvector from the autocorrelation matrix, wherein the transform base for the intra prediction mode is generated by using the calculated eigenvector.
4. The video encoding apparatus of claim 1 , wherein the correlation matrix calculator is configured to calculate the autocorrelation matrix for the collected prediction errors for the intra prediction mode, based on an equation of R c m = E [ P k m ( P k m ) T ] = 1 N m ∑ k = 1 N m P k m ( P k m ) T , wherein m denotes an index indicating the intra prediction mode of the current block, R c m denotes an autocorrelation matrix for a column vector signal of the collected prediction errors in which an intra prediction mode is determined as intra prediction mode m, N m denotes the number of blocks in which an intra prediction mode is determined as intra prediction mode m, among blocks which are encoded prior to the current block, and P k m denotes one prediction error block which is a k th element of P m denoting the collected prediction errors in which an intra prediction mode is determined as intra prediction mode m.
5. The video encoding apparatus of claim 1 , wherein the correlation matrix calculator is configured to calculate the autocorrelation matrix for the collected prediction errors for the intra prediction mode, based on an equation of R r m = E [ ( P k m ) T P k m ] = 1 N m ∑ k = 1 N m ( P k m ) T P k m , where m denotes an index indicating an intra prediction mode, R r m denotes an autocorrelation matrix for a row vector signal of the collected prediction errors in which an intra prediction mode is determined as intra prediction mode m, N m denotes the number of blocks in which an intra prediction mode is determined as intra prediction mode m, among blocks which are encoded prior to the current block, and P k m denotes one prediction error block which is a k th element of P m denoting the collected prediction errors in which an intra prediction mode is determined as intra prediction mode m.
6. A transform base generating apparatus for generating a transform base for an intra prediction mode of a current block, the transform base generating apparatus comprising: an intra prediction error collector configured to collect, for the intra prediction mode of the current block, prediction errors of respective blocks having the same intra prediction mode as the intra prediction mode of the current block, the respective blocks being encoded prior to encoding the current block; a correlation matrix calculator configured to calculate an autocorrelation matrix for the intra prediction mode by using (i) each first matrix corresponding to each of the collected prediction errors of each of the respective blocks for the intra prediction mode and (ii) each transpose matrix of said each first matrix, wherein the autocorrelation matrix for the intra prediction mode is generated based on an average of respective multiplications of said each first matrix and said each transpose matrix of said each first matrix; and an eigenvector calculator configured to calculate an eigenvector from the autocorrelation matrix, wherein the transform base for the intra prediction mode is generated based on the calculated eigenvector.
7. The transform base generating apparatus of claim 6 , wherein the transform base is a KLT-based transform base.
8. A video decoding apparatus, comprising: an intra prediction mode reader configured to extract an intra prediction mode of a current block to be decoded, from a bitstream; an intra prediction error collector configured to collect, for the intra prediction mode of the current block, prediction errors of respective blocks having the same intra prediction mode as the intra prediction mode of the current block, the respective blocks being encoded prior to encoding the current block; a transform base generator configured to generate a transform base for the intra prediction mode based on the collected prediction errors; an inverse transformer configured to inversely transform prediction error information of the current block by using the transform base for the intra prediction mode to generate an error block, the prediction error information being extracted from the bitstream; and a current block reconstructer configured to predict the current block to generate a predicted block by using neighboring pixels of the current block according to the intra prediction mode of the current block, and reconstruct the current block by adding the predicted block and the error block, wherein the transform base generator comprises a correlation matrix calculator configured to calculate an autocorrelation matrix for the intra prediction mode by using (i) each first matrix corresponding to each of the collected prediction errors of each of the respective blocks for the intra prediction mode and (ii) each transpose matrix of said each first matrix, wherein the autocorrelation matrix for the intra prediction mode is generated based on an average of respective multiplications of said each first matrix and said each transpose matrix of said each first matrix, and wherein the transform base for the intra prediction mode is generated based on the autocorrelation matrix for the intra prediction mode.
9. The video decoding apparatus of claim 8 , wherein the transform base generator further comprises: an eigenvector calculator configured to calculate an eigenvector from the autocorrelation matrix, wherein the transform base for the intra prediction mode is generated based on the eigenvector.
10. A video encoding method, comprising: collecting, for an intra prediction mode of a current block, prediction errors of respective blocks having the same intra prediction mode as the intra prediction mode of the current block, the respective blocks being encoded prior to encoding the current block; calculating an autocorrelation matrix for the intra prediction mode by using (i) each first matrix corresponding to each of the collected prediction errors of each of the respective blocks for the intra prediction mode and (ii) each transpose matrix of said each first matrix, wherein the autocorrelation matrix for the intra prediction mode is generated based on an average of respective multiplications of said each first matrix and said each transpose matrix of said each first matrix; predicting the current block to generate a predicted block by using neighboring pixels of the current block according to the intra prediction mode of the current block; generating a prediction error block of the current block according to a difference between the predicted block and the current block; generating a transform base for the intra prediction mode based on the autocorrelation matrix for the intra prediction mode; and transforming the prediction error block of the current block by using the transform base for the intra prediction mode.
11. A video decoding method, comprising: extracting an intra prediction mode of a current block to be decoded, from a bitstream; collecting, for the intra prediction mode of the current block, prediction errors of respective blocks having the same intra prediction mode as the intra prediction mode of the current block, the respective blocks being encoded prior to encoding the current block; calculating an autocorrelation matrix for the intra prediction mode by using (i) each first matrix corresponding to each of the collected prediction errors of each of the respective blocks for the intra prediction mode and (ii) each transpose matrix of said each first matrix, wherein the autocorrelation matrix for the intra prediction mode is generated based on an average of respective multiplications of said each first matrix and said each transpose matrix of said each first matrix; generating a transform base for the intra prediction mode based on the autocorrelation matrix for the intra prediction mode; inversely transforming prediction error information of the current block by using the transform base for the intra prediction mode to generate an error block, the prediction error information being extracted from the bitstream; predicting the current block to generate a predicted block by using neighboring pixels of the current block according to the intra prediction mode of the current block; and reconstructing the current block by adding the predicted block and the error block.
12. The video decoding method of claim 11 , wherein generating of the transform base comprises: calculating an eigenvector from the autocorrelation matrix, wherein the transform base for the intra prediction mode is generated based on the eigenvector.
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
December 9, 2010
February 23, 2016
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