System and method for efficient tile generation from complex raster data
AssigneeInternational Business Machines Corporation
InventorNenad Rijavec
Life of this patent
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Abstract
A system and method for accepting raster data from a Postscript or equivalent image data generator, identifying portions of the raster image which contain continuous tone data and linework data, dividing those portions into separate tiles and compressing the data within each tile by a compression method optimized for the type of image data within the tile. The compression algorithms are based upon conventional JPEG or LZW techniques, but enhanced to more efficiently process image data sets with large amounts of blank data.
Claims33
A method for compressing image data, comprising the steps of:
- identifying a plurality of image tiles within a composite image data set, wherein a mask data value indicating whether the pixel contains one of continuous tone image data or linework image data and a valid data value indicating whether the pixel contains any data at all are associated;
- characterizing an image data group within at least one image tile within the plurality of image tiles as one of linework image data if an aggregation of valid data values associated with pixels within the image data group is equal to true and an aggregation of mask data values associated with pixels within the image data group is equal to false or continuous tone image data;
- and
- encoding the image data group for at least the one image tile, wherein the image data group is encoded by an encoding algorithm selected based upon the characterization of the image data group.
An image data compression system, comprising:
- an image tile identifier for identifying a plurality of image tiles within a composite image data set, wherein a mask data value indicating whether the pixel contains one of continuous tone image data or linework image data and a valid data value indicating whether the pixel contains any data at all are associated;
- a tile data characterizer for characterizing an image data group within at least one image tile within the plurality of image tiles as one of linework image data if an aggregation of valid data values associated with pixels within the image data group is equal to true and an aggregation of mask data values associated with pixels within the image data group is equal to false or continuous tone image data;
- and
- a tile data encoder for encoding the image data group for at least the one image tile, wherein the composite image data set is encoded by an encoding algorithm selected based upon the characterization of the image data group.
A computer readable medium including computer instructions for compressing image data, the computer instructions comprising instructions for:
- identifying a plurality of image tiles within a composite image data set, wherein a mask data value indicating whether the pixel contains one of continuous tone image data or linework image data and a valid data value indicating whether the pixel contains any data at all are associated;
- characterizing an image data group within at least one image tile within the plurality of image tiles as one of linework image data if an aggregation of valid data values associated with pixels within the image data group is equal to true and an aggregation of mask data values associated with pixels within the image data group is equal to false or continuous tone image data;
- and
- encoding the image data group for at least one of the at least one image tile, wherein the composite image data set is encoded by an encoding algorithm selected based upon the characterization of the image data group.
Dependencies are inferred from the claim text.