Xerox Corporation

Sang-Chul Kang

Charles Michael Hains

Martin Sidney Maltz

Peter A Crean

Robert John Rolleston

Uoc H Nguyen

David E Rumph

George L Eldridge

Norman W Zeck

Chia-Hao Lee

William E Nelson

Abraham E Claproth

Zoltan Zvi Stroll

Kien T Nguyen

Stephen C Miller

A method and system are provided for producing a print that substantially corresponds to the colorimetric attributes of a corresponding proof for an electronic source file. The method and system entail creating a first raster file corresponding to the electronic source file and a second raster file corresponding to the proof. The first and second raster files are aligned to insure a spatial correlation, and a color conversion data structure is built by comparing the aligned first and second raster files. The color conversion data structure is then used to convert the first raster file to a color converted output file. The color converted output file is color transformed to an output file which is then used to produce the print. The print substantially corresponds to the colorimetric attributes of the corresponding proof for the electronic source file.

System and method for matching colorimetric attributes of a production print to a proof

The system and method reduces aliasing which is formed by the patterns that are introduced by the halftone screens used in the printer. The system and method provides halftone-specific anti-alias filters for obtaining optimal effective resolution in printed images. A method of reducing aliasing in a digital image includes providing a digital image; selecting a halftone screen for halftoning the digital image, wherein the halftone screen has a directional component associated with it; filtering the digital image with an antialiasing filter, the antialiasing filter having been designed to have a directional frequency response that is optimized for the directional component of the selected halftone screen; and halftoning the filtered digital image.

System and method of reducing aliasing in printed images

A method and apparatus for compressing and decompressing electronic documents, with maximum intradocument independence, and maximum flexibility in optimization of compression modes. The method includes receiving documents containing unknown combinations of a plural data types, including combinations of scanned data, computer rendered data, compressed data and/or rendering tags; dividing the received image into strips of blocks determining from the image itself, which data types are present in each block; compressing data of each data type present in each block with a compression method optimized for its data type. Scanned data may be further segmented into plural scanned data types, where each data type is compressed in said compressing data step with a compression method optimized for said scanned image data type. If the received data type is compressed data, the process may include the additional functions of determining a compression ratio thereof, and accepting the compressed data for use as, or decompressing and recompressing the data, based on acceptability of said compression ration determination. An instruction set is generated that allows detailed decompression instruction data and image data to be combined with transmitted compressed data. A data structure is shown, which segregates data types and instruction data, and allows for block to block and strip to strip processing independence.

Method for compressing digital documents with control of image quality and compression rate

A compression process of dividing each word to be compressed into least and most significant bits, and applying a different compression ratio to each. If the compression processes are lossy, both parts of the output can also be losslessly compressed before being output. Hierarchical vector quantization can be issued for either lossy compressor.

Two channel HVQ (hierarchical vector quantization) compression

A simplified method for rotating a digital image through a small angle without the need for interpolation is described. The image is divided into small, square blocks, arranged in horizontal rows where each block is exactly to the left or right of the other blocks in the row, and into columns where each block in the column is offset to the right by one pixel with respect to the next higher block. The rotation is then accomplished by moving the lower rows to the left so that the columns are exactly vertical, and by moving the rightmost columns in a downward direction so that each block is one pixel below the block to its left. The result is a rotation of the image through a small angle. There is a considerable simplification gained from not rotating the data within each block which results in a slight distortion of the image, but for small angles, this is not noticeable.

Small angle image rotation using block transfers

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Irvine, CA, United States of America

Sang-Chul Kang