Xerox Corporation

Eric S Nickell

Robert M Coleman

David E Rumph

Robert Roy Buckley

Charles Michael Hains

Michael F Plass

Russell Roger Atkinson

L Dale Green

James K Kenealy

Mark T Corl

Margaret Motamed

Matthew Tucker

An object optimized printing system and method comprises a page description language decomposing system, a command instruction and data generating system and an image output terminal controller. The PDL decomposition system inputs a print file defining a plurality of pages in the page description language and locates the plurality of objects forming each page and their object types. Based on the determine object types and any explicit rendering commands in the PDL file, the PDL decomposition system automatically generates rendering tags for each of the objects. The rendering tags are used to control the command instruction and data generating system, the IOT controller and/or the image output terminal to optimize the printing by the IOT on an object-by-object basis. Based on the objects and the generated rendering tags, the command instruction and data generating system generates the differing types of data and the command instructions on a scanline-by-scanline basis. The generated command instructions and data are output to the IOT controller scanline-by-scanline. The data output to the IOT controller includes metabit data which is generated from the rendering tags. The metabit data output to the IOT controller is used to control various subsystems of the IOT controller and the IOT to optimize the printing characteristics of the IOT for each differing object on each scanline.

Object optimized printing system and method

An object optimized printing system and method includes a page description language decomposing system, a command instruction and data generating system and an image output terminal controller. The PDL decomposition system inputs a plurality of pages in the page description language and locates the plurality of objects forming each page and their object types. Based on the determine object types and any explicit rendering commands, the PDL decomposition system automatically generates rendering tags for each of the objects. The rendering tags are used to control the command instruction and data generating system, the IOT controller and/or the IOT to optimize the printing by the IOT on an object-by-object basis. Based on the objects and the generated rendering tags, the command instruction and data generating system generates the differing types of data and the command instructions on a scanline-by-scanline basis. The generated command instructions and data are output to the IOT controller scanline-by-scanline. The data output to the IOT controller includes metabit data generated from the rendering tags. The metabit data is used to control various subsystems of the IOT controller and the IOT to optimize the printing characteristics, of the IOT for each differing object on each scanline. The metabits can optimize such processing subsystems as halftone generation, halftone screen size and angle, color space transformation, tone reproduction curve, IOT output correction and the like. Using this system, each page output by the IOT has the printing characteristics for each object within the page optimized to the object's types.

Every printing system has characteristic defects which detract from high quality printing. Xerographic printing systems show defects such as banding, mottled colors in large fill areas, trail-edge deletion and starvation where toner concentrations drop at certain color edges, misregistration, and so on. Ink jet printing systems can show ink bleeding, streaking in the direction of head movement, and so on. One approach to reducing printer defects is to refine the electro-mechanics for more precise printing. Another approach which works for predictable defects is to modify the digital data being sent to the printer to pre-compensate for the defect. The prior art does this to a limited extent for individual object types (strokes, fills, images, text, etc.) and for misregistered color edges (trapping). This invention extends the range of edge-related defects that can be both predicted and pre-compensated for. An embodiment of the invention is described which pre-compensates for defects such as trail-edge deletion, starvation, misregistration, halo, etc. by identifying runs of color which meet the criteria likely to cause the effect and applying a function f(edge-distance, object-type) to such runs to modify them appropriately. Both the prediction criteria and the functions applied are anamorphic (the scan direction and process direction are treated differently) and object-optimized (object attributes are taken into account). Further, both prediction criteria and applied correction functions allow user-settable input.

Anamorphic object optimized function application for printer defect pre-compensation

An object optimized printing system and method comprises a page description language decomposing system, a command instruction and data generating system and an image output terminal controller. The PDL decomposition system inputs a print file defining a plurality of pages in the page description language and locates the plurality of objects forming each page and their object types. Based on the determine object types and any explicit rendering commands in the PDL file, the PDL decomposition system automatically generates rendering tags for each of the objects. The rendering tags are used to control the command instruction and data generating system, the IOT controller and/or the image output terminal to optimize the printing by the IOT on an object-by-object basis. Based on the objects and the generated rendering tags, the command instruction and data generating system generates the differing types of data and the command instructions on a scanline-by-scanline basis. The generated command instructions and data are output to the IOT controller scanline-by-scanline. The data output to the IOT controller includes metabit data which is generated from the rendering tags. The metabit data output to the IOT controller is used to control various subsystems of the IOT controller and the IOT to optimize the printing characteristics of the IOT for each differing object on each scanline. The metabits can optimize such processing subsystems as halftone generation, halftone screen size and angle, color space transformation, tone reproduction curve, IOT output correction, and the like. Using this system, each page output by the IOT has the printing characteristics for each object within the page optimized to the object's types.

A simple method of anti-aliasing for edges near the fast scan direction is to replace the pixels on both sides of the transition in a scan with pixels of varying intermediate color. Thus, if there is an edge between red and blue areas, instead of there being an abrupt change from red to blue at the edge, there will be a number of pixels that slowly vary from mostly red to mostly blue, which will tend to make the jagged edge less obvious.

Efficient run-based anti-aliasing

A bitmap-based digital color printing method and system is described which automatically detects when a black object is to be printed and changes the Bit Block Transfer (BitBlt) method so that the black color becomes a mixture of black plus the background colorants, limited both by a clipping of one colorant against another and by an allowed maximum value for each remaining non-black separation. More specifically, the process reads the existing background color bits, does a first clip of one separation against another assuming that for correcting certain printing defects some separations are more important than others, and then does a second clip of remaining non-black separations to a pre-set maximum allowable amount. The result is an efficient way to control total colorant while allowing some separations precedence over others; with the result that the amount of colorant in one separation is dependent on or partially correlated with the amount of colorant in another. This preferentially limits colorants in a black object. As an example, reducing the amount of a high luminance separation (eg, yellow) relieves toner pile height problems without creating significant trapping problems. Therefore, in order to preferentially reduce yellow, the cyan or magenta components may be used to clip the yellow component in a first clipping step. By doing so, the maximum allowed colorant in both the cyan and magenta separations can be increased, which for some printing systems creates fewer visual defects in color prints.

Color bitmap merging of black objects using partially correlated

A bitmap-based digital color printing method and system is described which automatically detects when a black object is to be printed and changes the Bit Block Transfer (BitBlt) method so that the black color becomes a mixture of black plus the background colorants, limited by an allowed maximum non-black value for each separation. More specifically, the process determines, for each non-black separation, a maximum allowable amount to be used in black printing, reads the existing background color bits, and clips them if necessary to the allowed maximum before mixing them into the black color. The result will be a limitation on the total colorant amount of the black area, which improves some printer defects caused by too much colorant. The clipping can be accomplished at the bit level during the read-modify-write process if both the maximum and actual colors are represented with the same monotonic halftone dot specification, and are ANDed together to form the clipped bits. For many printing systems the resulting prints exhibit fewer visual defects. Single-color black objects printed as clipped process black exhibit greater density and gloss and create fewer printer defect problems such as misregistration and xerographic 'tenting'. Conversely, process black objects on white are printed as single-color black objects and do not exhibit objectionable problems such as color fringing, excessive colorant, and excessive gloss contrast with the background.

Color bitmap merging of black objects using separation maximum value

A software package is described which resides in a color printing system and which automatically intercepts and colorizes black and white documents (or re-colors color documents, if desired) that are sent to the color printer. The description includes pictorial flow charts and segments of code from an existing implementation in a Pascal-like language, implemented for documents expressed in a high-level page description language (PDL). The functionality of each major process in the software is explained in detail, including as examples the process of capturing and parsing user-specified modifications to the automatic coloring instructions, the process of coloring graphical objects according to their existing fill patterns, the process of coloring text and adding textual features such as dropshadows, and the process of coloring bitmaps.

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Bainbridge Island, WA, United States of America

Eric S Nickell