Method and apparatus for compressing and decompressing data
AssigneeImagination Technologies Limited
InventorSimon Fenney
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Abstract
The invention provides a method and apparatus for compressing and decompressing electronic image data, and in particular texture data. The compressed data comprises at least two sets of reduced size data, modulation data and modulation and discontinuity flags. The modulation and discontinuity flags determine how the modulation data is used, in combination with the reduced size data sets, in a decompression process. The invention allows for data decompression of textures including large color discontinuities.
Claims19
A machine-implemented method of producing image data from compressed source data, comprising:
- accessing, from a non-transitory machine readable medium, compressed source data comprising a respective set of representative colors, modulation data, and discontinuity data pertaining to regions of an image, for which a representation is to be constructed;
- determining a respective color set, comprising one or more colors, available for use in producing each element of the region of the image, the determining comprising blending two or more representative colors pertaining to multiple regions of the image to produce each color in the color set, if a discontinuity flag associated with the element indicates absence of a discontinuity, and if the discontinuity flag indicates presence of a discontinuity, then using only the representative colors of the region of the image containing the element in determining the respective color set for that element;
- and
- producing each element of the region of the image, using the color set by modulating selection of colors from the color set according to modulation data associated with that element of the region of the image.
A system for decompressing compressed image data, comprising:
- a source of blocks of compressed image data, the blocks having data for use in constructing a representation of a region of an image that was compressed to yield the blocks of compressed image data, the region comprising a plurality of pixels and the blocks containing compressed image data for neighboring pixels in the region;
- and
- a decompression unit operable to input the blocks of compressed image data, to produce a respective set of colors to be used in determining a value for each pixel of the plurality of pixels, wherein each set of colors is produced in dependence on a discontinuity flag from the blocks of compressed image data, and, for each pixel of the region, to blend a selection of colors from the respective set of colors for that pixel according to modulation data from the blocks of compressed image data.
A texture decompressor apparatus for decompressing compressed texture data, comprising:
- an input configured for receiving blocks of compressed texture data;
- an expander unit, coupled to the input, configured for expanding each reduced size data set to produce an expanded data set, the method of expansion for each element of the reduced size data sets dependent on the value of a corresponding discontinuity flag;
- and
- a combiner, coupled to the input and to the expanding means, configured for combining the expanded data sets using a modulation data and for generating an approximation to a portion of the original image data set.
Dependencies are inferred from the claim text.