Patent ID: 7554696
Filing Date: 2009-06-30
Classification: H04N

Abstract:
1. A device-specific, physical and optical dot-gain reducing method for multi-level color-image halftoning regarding the output of a selected color-imaging multi-level halftone output device with respect to which individual pixels within a dot may have different intensities, said method comprising based upon observed pixel-infeed-to-(multi-level)halftoning-pixel-output operational characteristics of such a device, creating a pixel-and-color-specific dot-gain reduction curve which relates, as data points for each output color of the device, selected corrections in device per-pixel pixel infeed intensity to different pre-selected, specific, multi-level, halftone geometric dot patterns of plural pixels including a contained subject pixel which is to be output from the device, where those dot patterns include a predetermined geometric pixel arrangement possessing (a) a central pixel, which is the mentioned subject pixel, and (b) the presence or absence of a defined collection and geometric distribution of immediately neighboring pixels, and further where those patterns collectively represent the halftone dot-pattern population characteristics of an expected multi-level, per-pixel-intensity-corrected, halftoned color image which is to be output by the device, at a point in the image-processing flow of a stream of color-image pixel data which is upstream from the region where color-image device outputting takes place, and downstream from where multi-level halftoning of that data occurs, and for each pixel in the data which is to be output ultimately to become a color-visible pixel, determining in which pre-selected multi-level, halftone dot pattern that pixel effectively lies and is associated as the contained subject pixel, and the output color intended for that pixel, relevant to said determining, and in relation to such a determined halftone dot pattern, appropriately applying to the associated, contained subject pixel, as the sole physical and optical dot-gain-reduction instrumentality, the created dot-gain reduction curve, and by said reduction-curve applying, reducing both physical and optical dot-gain contributions of the subject pixel in whatever multi-level halftoned image is associated with that subject pixel.