Xerox Corporation

William E Nelson

James Milo Sweet

Norman W Zeck

Peter A Crean

George L Eldridge

Remo J D'Ortenzio

Jon S McElvain

David E Rumph

Ronald E Rider

Sang-Chul Kang

Gregory W Zack

A method and system for predicting expansion difficulty and an expansion time required to perform print-time imaging operations. A print-ready compressed file may be generated by raster image processing of a job description file associated with a rendering job provided by a digital front end. The expansion time with respect to one or more expansion processes may be predicted by a linear equation during assembly of the compressed file. The linear equation may be formulated based on measured compression statistics that relate to profile data within the compressed file. The total expansion time with respect to the rendering job may be then computed by summing the results of the linear equations. The expansion time to perform the print-time imaging operations may be compared with an available time based on an image output terminal speed to improve performance of raster image processing.

Predicting an expansion difficulty and an expansion time required to perform a rendering operation

A method receives, at a processor of a printing apparatus, a variable information print job. The variable information print job is processed into upper planes of the record-specific objects, upper planes of the reusable objects, lower planes of the record-specific objects, and lower planes of the reusable objects. The method stores such objects within a storage medium of the printing apparatus. The method combines ones of the compressed upper planes of the record-specific objects and the compressed upper planes of the reusable objects corresponding to the record of the variable information print job using the processor to create a single compressed upper plane for the record within an output buffer of the printing apparatus and creates an ordered list (corresponding to the record) of lower plane tiles by assembling the compressed lower planes of the record-specific objects and the compressed lower plane reusable objects. The method performs a printing operation for the record of the variable information print job by decompressing multiple ones of the lower plane tiles in a predetermined order to form a lower plane of the record into an output raster page, decompressing the single compressed upper plane of the record into the output raster page, and outputting the output raster page to a printing engine of the printing apparatus to print the record of the variable information print job on print media.

Method and apparatus for improving raster image processing performance for variable information printing having reusable objects

There is disclosed in embodiments methods relating to the compression of printing hints. The method in embodiments generates a first set of image pixels having corresponding printing hints. The printing hints are then adjusted to produce a second set of image pixels processed in such a way that an end printed result is visually equivalent to a printed result using the first set of image pixels thereby reducing the entropy in the printing hints. The method improves the compression ratio of an image using printing hints by adjusting the printing hints of pixels that are zero or fully saturated. The printing hints are adjusted in such a way to reduce the complexity of the printing hints.

Method for compressing printing hint data sent to a printer

This invention relates to a method and apparatus for controlling image quality and compression ratios in image segmentation. More particularly, the invention is directed to an image segmenting system and method that analyzes and classifies pixel blocks of an image to determine the manner in which the image block should be compressed, e.g. with a lossy or a lossless technique. This approach, which assumes no apriori knowledge of the any specific region of the image, results in effective use of the various known compression techniques and provides improved overall compression ratios and image quality.

Method and apparatus for controlling image quality and compression ratios

A method for digital image compression of a raster image is disclosed which uses different compression methods for selected parts of the image and which dynamically adjusts compression and segmentation parameters to control tradeoff of image quality and compression. The image is encoded into a single data stream for efficient handling by disk, memory and I/O systems. This system provides a stable feedback loop that manages to a fine granularity (typically 8&times;8 pixel blocks) the compression of image data so as to be compliant with a plurality of compression constraints; the management of an incremental bias toward more aggressive compression that selectively applies the more aggressive compression methods to blocks that are the most tolerant with respect to visible artifacts; and the adjustable segmentation and compression parameters used to control the image compression.

Method for compressing digital documents with control of image quality subject to multiple compression rate constraints

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

An improved sliding window dictionary-based compression method limits the data within the sliding window searched to data strings occurring at each discrete match location within a plurality of predefined discrete match locations, the plurality of predefined discrete match locations comprising a set of non-continuous data positions within the window of data.

Sliding window compression method utilizing defined match locations

A method of producing a raster font from a contour font entailing the steps of deriving font metrics and character metrics of font characters in terms of arbitrary font units; scaling the font characters to a selected size and output resolution (pixels per unit length); altering the thickness of vertical and horizontal strokes of each character to a desired thickness, from the measured font metrics and character metrics, and including a difference applied to the thickness of the strokes by the printer process, to cause the strokes to be close to an integer number of pixels and thickness and to compensate for thinning and thickening which the printing engine might produce; bringing the leading and trailing edges of the characters to integer pixel locations, where such locations are based on and scaling the character between the leading and trailing edges proportionally therebetween, and producing a rasterized font from the altered contour font character.

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Penfield, NY, United States of America

William E Nelson