Apple Inc.

Randall G Guay

Kok S Chen

James C Zandee

If we assume that images to be printed will consist of a combination of natural images and computer generated images, we would like the natural images to map to the closest printable colors, and the computer generated images to map to the saturated printer colors. Usually, we cannot tell the source of a color specification, so one algorithm must suffice for both conditions. A method to combine the two is presented. First, the printable colors are measured is some device independent color sapce, such as L*a*b*. Next, the range of colors from some reference color CRT, consisting of the colors from black to monitor saturates, and the colors between, then from saturates to white, and the colors between, are calculated. The saturates are assigned colors based on what printable color a user would like to get when the user asks for a saturated CRT color. A good coice would be the color space defined by CCIR 709, but any color space could be used. This gives us the printer's representation of the outer range of the color gamut of the CRT. Next, a table is generated which subsample all colors available to the specified color space. This table fills in entries within the color gamut of the target printer with the closest printable color. Colors out of the printer's gamut are represented by an averaging of the printable colors and of the outer range of colors assigned for the saturates. A requested color is converted to the reference color space, then looked up in the table, and the resulting color specification is sent to the printer.

Subjectively pleasing color gamut mapping in a color computer graphics

A color printing system with reduced bleed includes a computer and a color printer. The computer has a digital processor and memory accessed by the digital processor, where the memory stores printable objects selected from the group comprising graphic objects and non-graphic objects and pixel maps corresponding to the graphic objects and the non-graphic objects. The color printer is coupled to the computer and is capable of printing the pixel maps using color pixels and black pixels. An image processor implemented on the computer identifies the graphic objects among the printable objects, adjusts pixel densities of the graphic objects, and renders the printable objects as the pixel maps, such that black pixel densities of pixel maps of the graphic objects are reduced without reducing black pixel densities of pixel maps of the non-graphic objects. A method of the present invention includes the steps of identifying graphic objects among printable objects, adjusting color information of the graphic objects if bleed reduction criteria are met, and developing printer control information from the printable objects that can provide for a lower black pixel density for the graphic objects due to the adjustment of the color information of the graphic objects.

Color printing system and method with reduced bleed

A method for object based color matching when printing color documents. Objects are anything that can be drawn, and include text, rectangle, oval, region, polygon, and PixMaps. Color matching is performed on each object in a page prior to rendering the object into a pixel map. This is accomplished by setting up multiple concurrent color matching sessions that have different rendering intents. Depending upon the object type, a color matching session with a particular rendering intent is used to perform color matching on the object.

Method for object based color matching when printing a color document

A method of smoothing a color lookup table minimizes inappropriate shifts away from gray, at the same time reducing the effect of measurement errors and enabling interpolation between the lookup table data points to be performed efficiently. More particularly, data in a preliminary lookup table, comprising a three-dimensional data array in which a location of each data point is designated by a unique tuple, is smoothed so as to satisfy predetermined constraints. A resulting three-dimensional lookup table relates source device colors and destination device colors in a computer graphics system in which a color image source device and a color image destination device have non-coincident color gamuts. The method is performed by, beginning at a data point representing white and concluding at a data point representing black, comparing a data point representing an adjacent shade of gray to neighboring data points and, if a color component of one or more of the neighboring data points differs in value from the same color component of the data point by more than a predetermined amount, adjusting the value of the color component of the one or more neighboring data points such that the color component of the one or more neighboring data points does not differ in value from the color component of the data point by more than the predetermined amount. Related data points whose tuples differ from a tuple of the data point in only one dimension are then compared to neighboring data points. The foregoing steps are repeated until the entire lookup table has been smoothed.

Color map tables smoothing in a color computer graphics system avoiding

An apparatus and method for imaging using context sensitive pixel modulation wherein a modulator dynamically examines the neighboring pixels to the current pixel being imaged and uses the neighboring pixel information in determining the specific modulation pattern for the current pixel.

Method and apparatus for context sensitive post processing to select an

An apparatus and method for producing high definition output images using an encoding scheme for differentiating between differing data types and context sensitive pixel modulation for dynamically shifting pixel growth direction during post-processing manipulation of the data.

Method and apparatus for high definition imaging

An apparatus and method for enabling intelligent post-processing of differing data types wherein different types of data are encoded with different sets of values such that a post-processing apparatus is able to recognize and delineate between the different types and perform post-processing procedures on only the appropriate type.

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Cupertino, CA, United States of America

Randall G Guay