US 5,999,710 AGranted

Merge plane generation for a data processing pipeline

AssigneeHewlett-Packard Company

InventorsMarcus A. Smith, Christopher T. Creel, Jason Main

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Abstract

A print data processing pipeline for use in a color electrophotographic printer optimizes print quality and minimizes memory usage by separately processing lossy and lossless print data. Lossy print data may include print data for images and lossless print data may include print data for text, line art, and graphics. Partitioning print data into lossy and lossless elements allows application of the print data compression operations optimized for each type of print data. High compression ratios can be achieved on lossy print data by applying visually lossless compression operations designed for the lossy print data. In addition, high compression ratios can be achieved on the lossless print data by applying lossless compression operations designed for the lossless print data. A merge unit combines the lossy and lossless print data streams after decompression to reconstruct the original image using merge data. The merge data is generated in an image processing operation which accounts for the different transparency modes of the page description language print data so that the correct foreground and background placement of objects is maintained. Placement of the color space conversion operation and the halftone operation relative to the merge operation, further optimizes the print quality while minimizing memory usage. The print data processing pipeline includes a direct memory access controller which has the capability to allow print data to be selectively directed to the lossy or lossless compressor/decompressor, the color space converter, or the merge unit.

Claims20

Dependent claims

In a print data processing pipeline for separately processing print data, including print data expressed in a page description language having transparency modes and with said print data used to generate a stream of print data elements including lossless print data elements and lossy print data elements, each of said lossless print data elements and said lossy print data elements having a first transparency mode and, alternatively, a second transparency mode, a method for generating merge data elements corresponding to said print data elements and used to merge said lossless print data elements and said lossy print data elements after said separate processing, said method comprising the steps of:

determining if a transparency mode of a one of said print data elements corresponds to said first transparency mode;
determining if said one of said print data elements corresponds to a white print data element if said one of said print data elements includes said transparency mode corresponding to said second transparency mode;
determining if said one of said print data elements corresponds to said lossy print data elements if said one of said print data elements includes said transparency mode corresponding to said second transparency mode and corresponds to said white print data element;
setting a one of said merge data elements corresponding to said one of said print data elements to select from said lossless print data elements if said one of said print data elements includes a transparency mode corresponding to said second transparency mode, corresponds to said white print data element, and corresponds to said lossy print data elements;
and
setting said one of said merge data elements corresponding to said one of said print data elements to select from said lossy print data elements if said one of said print data elements includes a transparency mode corresponding to said second transparency mode, corresponds to said white print data element, and corresponds to said lossless print data elements.

3 more elements

A print data processing pipeline for processing print data, comprising:

a processor for generating print data elements including lossless raster print data elements and lossy raster print data elements from said print data, said print data includes print data expressed in a page description language having transparency modes, said processor includes a means for generating merge data elements corresponding to said print data elements responsive to said transparency modes of said print data elements;
a lossless compressor/decompressor configured to receive said lossless raster print data elements to generate compressed lossless raster print data elements and configured to receive said compressed lossless raster print data elements to generate decompressed lossless raster print data elements;
a lossy compressor/decompressor configured to receive said lossy raster print data elements to generate compressed lossy raster print data elements and configured to receive said compressed lossy raster print data elements to generate decompressed lossy raster print data elements;
and
a merge unit configured to receive said decompressed lossless raster print data elements and said decompressed lossy raster print data elements to generate merged lossless and lossy raster print data using said merge data elements.

2 more elements

A printer, comprising:

a processor for generating print data elements including lossless raster print data elements and lossy raster print data elements from said print data, said print data includes print data expressed in a page description language having transparency modes, said processor includes a means for generating merge data elements corresponding to said print data elements responsive to said transparency modes of said print data elements;
a direct memory access controller operatively coupled to said processor, said direct memory access controller configured to receive at least one of said lossless raster print data elements, said lossy raster print data elements, and said merge data elements from said processor and configured to send at least one of said lossless raster print data elements, said lossy raster print data elements, and said merge data elements;
a lossless compressor/decompressor coupled to said direct memory access controller, said lossless compressor/decompressor configured to receive said lossless raster print data elements to generate compressed lossless raster print data elements and said lossless compressor/decompressor configured to receive said compressed lossless raster print data elements to generate decompressed lossless raster print data elements;
a lossy compressor/decompressor coupled to said direct memory access controller, said lossy compressor/decompressor configured to receive said lossy raster print data elements to generate compressed lossy raster print data elements and configured to receive said compressed lossy raster print data elements to generate decompressed lossy raster print data elements;
and
a merge unit configured to receive said decompressed lossless raster print data elements and said decompressed lossy raster print data elements to generate merged lossless and lossy raster print data using said merge data elements.

3 more elements

Dependencies are inferred from the claim text.