US 6,959,116 B2 · Largest magnitude indices selection for (run, level) encoding of a block coded picture

Abstract

Transform coefficients for blocks of pixels in an original picture are quantized to produce respective sets of quantization indices for the blocks of pixels. The quantization indices for at least some of the blocks are produced by using a quantization step size that is not uniform within each block. Largest magnitude quantization indices are selected from the respective sets of quantization indices for (run, level) encoding to produce the (run, level) encoded picture. For example, MPEG-2 coded video includes a set of non-zero AC discrete cosine transform (DCT) coefficients for 8×8 blocks of pixels. For scaling the MPEG-2 coded video, non-zero AC DCT coefficients are removed from the MPEG-2 coded video to produce reduced-quality MPEG-2 coded video that includes no more than a selected number of largest magnitude quantization indices for the non-zero AC DCT coefficients for each 8×8 block.

Claims20

Dependent claims

A method of producing a (run, level) encoded picture from an original picture, said method comprising:

producing respective sets of transform coefficients for blocks of pixels in the original picture;
quantizing transform coefficients in the respective sets of transform coefficients to produce respective sets of non-zero quantization indices for the blocks of pixels, wherein the non-zero quantization indices for at least some of the blocks are produced by using a quantization step size that is not uniform within said at least some of the blocks;
inspecting magnitudes of the non-zero quantization indices for selecting a limited number of largest magnitude non-zero quantization indices for the blocks of pixels in the respective sets of quantization indices to produce respective sets of selected quantization indices having non-zero levels for the blocks of pixels;
and
(run, level) encoding quantization indices from the respective sets of selected quantization indices to produce the (run, level) encoded picture.

2 more elements

A method of scaling non-scalable MPEG-2 coded video to produce reduced-bandwidth, reduced-quality MPEG-2 coded video, the non-scalable MPEG-2 coded video including a set of non-zero AC discrete cosine transform (DCT) indices for 8×8 blocks of the non-scalable MPEG-2 coded video, the non-zero AC discrete cosine transform (DCT) indices for at least some of the 8×8 blocks of the non-scalable MPEG-2 coded video having been produced by using a quantization step size that is not uniform within said at least some of the blocks, said method comprising:

inspecting magnitudes of the non-zero quantization indices for removing non-zero AC DCT indices from the non-scalable MPEG-2 coded video so that the reduced-quality MPEG-2 coded video includes no more than a selected number of largest magnitude non-zero quantization indices for the non-zero AC DCT indices for each 8×8 block.

A digital computer programmed for producing a (run, level) encoded picture from an original picture, wherein the digital computer comprises at least one processor programmed for:

producing respective sets of transform coefficients for blocks of pixels in the original picture;
quantizing transform coefficients in the respective sets of transform coefficients to produce respective sets of non-zero quantization indices for the blocks of pixels, wherein non-zero quantization indices for at least some of the blocks are produced by using a quantization step size that is not uniform within said at least some of the blocks;
inspecting magnitudes of the non-zero quantization indices for selecting a limited number of largest magnitude non-zero quantization indices from the respective sets of non-zero quantization indices to produce respective sets of selected quantization indices having non-zero levels for the blocks of pixels;
and
(run, level) encoding quantization indices from the respective sets of selected quantization indices to produce the (run, level) encoded picture.

2 more elements

A digital computer for scaling non-scalable MPEG-2 coded video to produce reduced-bandwidth, reduced-quality MPEG-2 coded video, the non-scalable MPEG-2 coded video including a set of non-zero AC discrete cosine transform (DCT) quantization indices for 8×8 blocks of the non-scalable MPEG-2 coded video, the non-zero AC discrete cosine transform (DCT) indices for at least some of the 8×8 blocks of the non-scalable MPEG-2 coded video having been produced by using a quantization step size that is not uniform within said at least some of the blocks, the digital computer comprising a processor programmed for inspecting magnitudes of the non-zero AC DCT quantization indices for removing non-zero AC DCT quantization indices from the non-scalable MPEG-2 coded video so that the reduced-quality MPEG-2 coded video includes no more than a selected number of largest magnitude non-zero AC DCT quantization indices for the non-zero AC DCT quantization indices for each 8×8 block.

Dependencies are inferred from the claim text.

Largest magnitude indices selection for (run, level) encoding of a block coded picture

Life of this patent

Largest magnitude indices selection for (run, level) encoding of a block coded picture

Life of this patent

Abstract

Claims20