Guaranteed Data Compression
AssigneeImagination Technologies Limited
InventorsSimon Fenney, Linling Zhang
Life of this patent
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Abstract
Lossy methods and hardware for compressing data and the corresponding decompression methods and hardware are described. The lossy compression method comprises dividing a block of pixels into a number of sub-blocks and then analysing, for each sub-block, and selecting one of a candidate set of lossy compression modes. The analysis may, for example, be based on the alpha values for the pixels in the sub-block. In various examples, the candidate set of lossy compression modes comprises at least one mode that uses a fixed alpha channel value for all pixels in the sub-block and one or more modes that encode a variable alpha channel value.
Claims20
A lossy method of compressing data comprising:
- dividing a block of pixels into a plurality of sub-blocks;
- and
- for each sub-block:
- analysing an alpha channel value for each pixel in the sub-block to select a lossy compression mode from a set of candidate lossy compression modes, wherein the set of candidate lossy compression modes comprises two or more lossy compression modes including at least one compression mode which uses a fixed alpha channel value for all pixels in the sub-block;
- and
- compressing the sub-block using the selected lossy compression mode.
A method of data decompression comprising:
- unpacking data from a compressed data block to generate compressed data for a plurality of sub-blocks;
- for each sub-block:
- identifying a compression mode from a block mode field within the compressed data block, wherein the compression mode is one of a set of candidate lossy compression modes, the set of candidate lossy compression modes comprising two or more lossy compression modes including at least one compression mode which uses a fixed alpha channel value for all pixels in the sub-block;
- and
- decompressing the sub-block using a decompression mode corresponding to the selected compression mode.
An integrated circuit manufacturing system comprising:
- a non-transitory computer readable storage medium having stored thereon a computer readable description of an integrated circuit that describes a data compression unit,
- a layout processing system configured to process the integrated circuit description so as to generate a circuit layout description of an integrated circuit embodying the data compression unit;
- and
- an integrated circuit generation system configured to manufacture the data compression unit according to the circuit layout description,
- wherein the data compression unit comprises:
- hardware logic arranged to dividing a block of pixels into a plurality of sub-blocks;
- hardware logic arranged, for each sub-block, to analyse an alpha channel value for each pixel in the sub-block to select a lossy compression mode from a set of candidate lossy compression modes, wherein the set of candidate lossy compression modes comprises two or more lossy compression modes including at least one compression mode which uses a fixed alpha channel value for all pixels in the sub-block;
- and
- a data compression element arranged to compress the sub-block using the selected lossy compression mode.
Dependencies are inferred from the claim text.