Xerox Corporation

Robert M Coleman

Eric S Nickell

David E Rumph

Robert Roy Buckley

Charles Michael Hains

Michael F Plass

Russell Roger Atkinson

L Dale Green

James K Kenealy

Mark T Corl

Leland D Green

Margaret Motamed

Matthew Tucker

A printing system for use in printing objects of any of a plurality of different object types includes a printer; and a printer control device with a user interface having a first option for associating printer-independent print-quality characteristics with a selected object type to be printed by the printer. A printer-independent print-quality characteristic is an instruction associated with an element, such as object type, in an electronic page which indicates printer-independent features that are preferentially emphasized when printing the element. Examples of printer-independent print quality characteristics include 'make sharp edges', 'reduce mottle', &#x201c;distinguish neighboring colors&#x201d;, &#x201c;reduce moir&#xe9;&#x201d;, &#x201c;distinguish tone and edges&#x201d;, &#x201c;maximum tone depth&#x201d;, &#x201c;perceptual colors&#x201d; and &#x201c;compress without loss of detail&#x201d;. The printing system may also include a device for retrieving printer-independent print-quality characteristics associated with a document to be printed by the printer and for associating printer-dependent imaging actions with the printer-independent print-quality characteristics.

Printing method employing printer-independent print quality characteristics

Printing system employing printer-independent print quality characteristics

A printing system for use in printing objects of any of a plurality of different object types includes a printer; and a printer control device with a user interface having a first option for associating printer-independent print-quality characteristics with a selected object type to be printed by said printer. A printer-independent print-quality characteristic is an instruction associated with an element, such as object type, in an electronic page which indicates printer-independent features that are preferentially emphasized when printing the element. Examples of printer-independent print quality characteristics include 'make sharp edges', 'reduce mottle', &#x201c;distinguish neighboring colors&#x201d;, &#x201c;reduce moir&#xe9;&#x201d;, &#x201c;distinguish tone and edges&#x201d;, &#x201c;maximum tone depth&#x201d;, &#x201c;perceptual colors&#x201d; and &#x201c;compress without loss of detail&#x201d;. The printing system may also include a device for retrieving printer-independent print-quality characteristics associated with a document to be printed by said printer and for associating printer-dependent imaging actions with the printer-independent print-quality characteristics.

Printing system and method

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

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 deplete 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. If a printer defect occurs predictably, it is possible to pre-compensate for the defect by modifying the digital signal in such a way that the modifications cancel out or hide the expected defect. However, most printing defects, while statistically predictable, vary over time in the severity and extent of the defect. Some defects, such as misregistration, may vary in severity and direction with each print, because the defect is caused in part by paper feeding and shifting during printing. Other defects, such as trail-edge deletion, starvation, halo, tenting, etc. may change more slowly because they are controlled in part by environmental conditions such as humidity or definable printing conditions like paper type. The invention proposes a method whereby defects that vary sufficiently slowly in a particular printing system are measured for extent and severity at appropriate intervals, and the measurements are used to modify correction functions applied to the digital data to pre-compensate for these defects. In this way, the corrections applied will track more precisely the current extent and direction of the defects they are correcting.

Achieving system stability in anamorphic printer defect pre-compensation

A digital color printing method and system is described which automatically detects when a neutral grey object is commanded to be printed, and changes the composition of the neutral color depending on the previous value of the neutral grey object and on the presence or absence of non-black colorants in the background color at the position on the page at which the neutral object is commanded to be printed. A single-color neutral object which is commanded to be printed at a position in which there is a previously rendered color background which contains non-black colorants may automatically have its neutral color changed from a single-color neutral to a process neutral containing at least one non-black colorant such as cyan, magenta, or yellow, said process neutral chosen to have equivalent visual density and neutrality as the previous single-color neutral value. Conversely, a process neutral grey object which is commanded to be printed at a position in which the background does not contain non-black colorants may automatically have the neutral color changed from process neutral to single-color neutral, said single-color neutral chosen to have the equivalent visual density as the process neutral. For many printing systems the resulting prints exhibit fewer visual defects. Neutral objects printed on top of a color field are printed as process neutral and thereby may exhibit a greater gloss and show fewer problems caused by the misregistration of separations or other printer defects, such as white fringes around the neutral objects. Conversely, neutral objects not on a color background are printed as single-color neutral objects and therefore do not exhibit objectionable process neutral problems such as color fringing, excessive colorant, and excessive gloss contrast with the background.

Color printing yielding a background dependent neutral gray image (i.e. intelligent gray)

A digital color printing method and system is described which automatically detects when a black object is commanded to be printed, and changes the composition of the black color depending on the presence or absence of non-black colorants in the background color at the position on the page at which the edge of the black object is commanded to be printed. A single-color black object which is commanded to be printed at a position in which there is a previously rendered color background which contains non-black colorants will automatically have the composition of its black color changed from single-color black to process black composed of black plus non-black colorants such as cyan, magenta, and yellow. Conversely, a process black object which is commanded to be printed at a position in which the background does not contain non-black colorants will automatically have the composition of the black changed from process black to single-color black. For many printing systems the resulting prints exhibit fewer visual defects. Black objects printed on top of a color field are printed as process black and thereby exhibit a greater density and gloss and show fewer problems caused by the misregistration of separations or other printer defects, such as white fringes around the black objects. Conversely, black objects not on a color background are printed as single-color black objects and therefore do not exhibit objectionable process black problems such as color fringing, excessive colorant, and excessive gloss contrast with the background.

Color printing yielding a background dependent black image (i.e. intelligent black)

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 method is described for printing a colorant controlled neutral black object in a bitmap-based digital color printing system. The method is useful in systems where the black colorant is not sufficiently opaque to hide non-neutral combinations of non-black colorants mixed into the black color. Black colors in a color printing system can be composed either of black colorant only or of black plus non-black colorants such as cyan, magenta, and yellow. If the non-black colorants are not mixed in nearly equal quantities, they will add hue to the black color. A sufficiently opaque black colorant can hide this objectionable non-black hue. However, in cases where the black colorant is not opaque enough, it is important to use equal or nearly equal combinations of cyan, magenta, and yellow so that little net hue will be introduced into the black color. Equally important in some printing systems is the ability to control the amount of total colorant used in forming a process black color. The invention proposes an efficient method for producing a colorant controlled, neutral black color when merging a black object into a color background for printing. The method involves reading the existing non-black background bits into a buffer, mixing them together and masking them to reduce the total colorant amount, or counting the ON bits and choosing a table entry based on this total, and outputting them again to the bitmap for printing.

Creation of colorant controlled neutral black objects in a bit map

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 predictable printer defects is to modify the digital data being sent to the printer to pre-compensate for the defect. One pre-compensation method identifies runs of color which meet the criteria likely to cause a printing defect and applies a function f(edge-distance, object-type) to such runs to modify them appropriately. However, if multiple defects are being corrected, an efficient method is needed to identify potential defects since a normal search procedure performed on a band of collected runs one at a time for each defect is time-consuming. Instead, a method is described by which modules responsible for detecting and correcting each defect register patterns of runs with a search module that are predicted to trigger defects. These registered patterns can then be applied as keys to a lookup table to quickly find if a printer defect pattern has been found, and which correction module to call to pre-compensate for the defect.

Efficient identification of predicted printer defects for anamorphic

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.

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Altadena, CA, United States of America

Robert M Coleman