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US 8,576,450 B2Granted
Replacing a defective colorant
AssigneeHewlett-Packard Development Company, L.P.
InventorsMatthew A Shepherd, Vanessa Verzwyvelt
Life of this patent
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Abstract
A system and methods for modifying the values of halftoned image pixels to replace a defective colorant with at least one non-defective colorant.
Claims22
A method of forming an image using a plurality of device-dependent colorants, comprising:
- receiving at least one raster of halftoned image pixels each having a discrete value for each of the colorants;
- for a raster associated with a defective colorant, modifying the values of the pixels to replace the defective colorant with an added amount of at least one non-defective colorant, the added amount for each individual pixel determined at least in part from a local density of the defective colorant at the corresponding pixel, the added amount having a predetermined non-linear relationship to the local density.
A printing system for printing color image data using a plurality of colorants, comprising:
- a plurality of print elements each configured to emit drops of one of the colorants to print halftoned pixels of a raster of the data, each pixel having a drop value for each of the colorants;
- a detector to identify a defective one of the print elements;
- a color replacer to modify the drop values of the pixels to replace the colorant of the defective print element with an added amount of colorant from at least one non-defective print element, the added amount determined for each individual pixel at least in part from a local density at the individual pixel of the colorant of the defective print element, the added amount having a predetermined non-linear relationship to the local density.
A method of forming an image using a plurality of device-dependent colorants, comprising:
- transforming a raster of halftoned image pixels each having one of N discrete values for each of the colorants to a human-vision-equivalent raster that replaces a defective one of the colorants by, for each pixel,
- converting the value for each non-defective colorant to a count, and adding the count to a total count for that non-defective colorant,
- converting the value for the defective colorant to a second count for at least one of the non-defective colorants, and adding the second count to the total count for that non-defective colorant, and
- re-halftoning the total counts of the non-defective colorants to generate a new value for the pixel.
1 more element
Dependencies are inferred from the claim text.