Low complexity and unified transforms for video coding
AssigneeNtt Docomo, Inc.
InventorFrank Jan Bossen
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Abstract
A method and apparatus is disclosed herein for decoding data (e.g., video data) using transforms. In one embodiment, the decoding process comprises scaling a block of coefficients using a scaling factor determined for each coefficient by computing an index for said each coefficient and indexing a look-up table (LUT) using the index. The index is based on a quantization parameter, a size of the block of coefficients, and a position of said each coefficient within the block. The method also comprises applying a transform to the block of scaled coefficients.
Claims14
A decoding method including:
- computer implemented steps performed by a processor of a computer system to implement the following steps:
- receiving a block of coefficients relating to a block of video information to be displayed which has been transformed and quantized for compression of the video information:
- providing a single, one dimensional look-up table (LUT) which consists of a single group of scaling factors applicable for scaling of coefficients of different block sizes;
- computing an index for each coefficient, the index being a function of a quantization parameter, a size of the block of coefficients, and a position of said each coefficient within the block;
- indexing the LUT, using the computed index, to determine a scaling factor in the LUT applicable for scaling of said each coefficient;
- scaling the block of received coefficients, using the determined scaling factors, to inversely quantize the block of received coefficients;
- and
- applying a vertical transform and a horizontal transform to the block of scaled coefficients in order to reconstruct a signal of the block video information for display of the video signal, where basis vectors of the vertical and horizontal transform are
- 1
- 1
- 1
- 1
- 5/4
- ½
- −½
- − 5/4
- 1
- −1
- 1
- −1
- ½
- − 5/4
- 5/4
- −½
- or transpose thereof.
A decoder for decoding a block of coefficients relating to a block of video information to be displayed which has been transformed and quantized for compression of the video information, the decoder comprising:
- a memory which stores a single, one dimensional look-up table (LUT) which consists of a single group of scaling factors applicable for scaling of coefficients of different block sizes;
- an index calculator configured to compute an index for each coefficient, the index being a function of a quantization parameter, a size of the block of coefficients, and a position of said each coefficient within the block;
- an indexer configured to index the LUT, using the computed index, to determine a scaling factor in the LUT applicable for scaling of said each coefficient;
- a scaler configured to scale the block of received coefficients, using the determined scaling factor, to inversely quantize the block of received coefficients;
- and
- an inverse transformer configured to apply a vertical transform and a horizontal transform to the block of scaled coefficients in order to reconstruct a signal of the block video information for display of the video signal, wherein basis vectors of the vertical and horizontal transforms are
- 1
- 1
- 1
- 1
- 5/4
- ½
- −½
- − 5/4
- 1
- −1
- 1
- −1
- ½
- − 5/4
- 5/4
- −½
- or transpose thereof.
A computer-readable medium, wherein the computer-readable medium is hardware, storing instructions which, when executed by a system, cause the system to:
- receive a block of coefficients relating to a block of video information to be displayed which has been transformed and quantized for compression of the video information;
- provide a single, one dimensional look-up table (LUT) which consists of a single group of scaling factors applicable for scaling of coefficients of different block sizes;
- compute an index for each coefficient, the index being a function of a quantization parameter, a size of the block of coefficients, and a position of said each coefficient within the block;
- index the LUT, using the computed index, to determine a scaling factor in the LUT applicable for scaling of said each coefficient;
- scale the block of received coefficients, using the determined scaling factor, to inversely quantize the block of received coefficients;
- and
- apply a vertical transform and a horizontal transform to the block of scaled coefficients in order to reconstruct a signal of the block video information for display of the video signal, wherein basis vectors of the vertical and horizontal transforms are
- 1
- 1
- 1
- 1
- 5/4
- ½
- −½
- − 5/4
- 1
- −1
- 1
- −1
- ½
- − 5/4
- 5/4
- −½
- or transpose thereof.
A decoder for decoding a block of coefficients relating to a block of video information to be displayed which has been transformed and quantized for compression of the video information, the decoder comprising:
- means for storing a single, one dimensional look-up table (LUT) which consists of a single group of scaling factors applicable for scaling of coefficients of different block sizes;
- means for computing an index for each coefficient, the index being a function of a quantization parameter, a size of the block of coefficients, and a position of said each coefficient within the block;
- means for indexing the LUT, using the computed index, to determined a scaling factor in the LUT applicable for scaling of said each coefficient, wherein indexing is independent of the block size;
- means for scaling the block of received coefficients, using the determined scaling factor in the LUT applicable for scaling of said each coefficient;
- and
- means for applying a vertical transform and a horizontal transform to the block of scaled coefficients in order to reconstruct a signal of the block video information for display of the video signal, wherein basis vectors of the vertical and horizontal transforms are
- 1
- 1
- 1
- 1
- 5/4
- ½
- −½
- − 5/4
- 1
- −1
- 1
- −1
- ½
- − 5/4
- 5/4
- −½
- or transpose thereof.
Dependencies are inferred from the claim text.