Intelligent GCR/UCR process to reduce multiple colorant moire in color printing
AssigneeXerox Corporation
InventorsThyagarajan Balasubramanian, Reiner Eschbach
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Abstract
A processing system for preparing a plural separation document image for printing, including a process for mitigation or reduction of three color moiré. An approximation of moiré amplitude is calculated, and compared to a reference. Where three color moiré mitigation is desirable, black is removed and replaced with other separation colors.
Claims20
A processing system for preparing a document image for printing, said document image to be described by image signals in plural separations including black, and controlling application of black addition thereto to mitigate three color moiré, including:
- receiving the image signals in plural separations;
- calculating an approximation of moiré amplitude from the received image signals;
- comparing moiré amplitude with at least one reference value;
- for location where moiré amplitude unfavorably compares with said reference value, controlling black addition to said plural separations and the image signals in said plural separations to limit three color moiré.
In a calibrated printing system including black addition and undercolor removal, preparing a document image for printing, said document image to be described by image signals in plural color separations and a black separation, and varying the images signals to control three color moiré, including:
- receiving the image signals in plural separations including black;
- calculating an approximation of moiré amplitude from the received image signals;
- comparing moiré amplitude with at least one reference value;
- for location where said comparing indicates an undesired image moiré artifact, adjusting a color pixel defined by said plural separations to limit three color moiré.
In a calibrated printing system including black addition and undercolor removal, an for which, a calibration process generates a calibration table relating device independent colors to device dependent colors, a said calibration process including a method of mitigating three color moiré, including:
- receiving and printing a set of calibration image signals in plural separations including black, after black addition and undercolor removal;
- determining whether undesirable three color moiré is present in said printed calibration image signals;
- generating a moiré mitigation strategy, substituting cyan, magenta and yellow pixels for black pixels;
- storing said strategy as part of a calibration table generated for said calibrated printing systems.
In a calibrated printing using more than three printing colorants, preparing a document image for printing, said document image to be described by image signals in plural color and varying the images signals to control three color moiré, including:
- receiving the image signals in plural separations;
- calculating an approximation of moiré amplitude from the received image signals;
- comparing moiré amplitude with at least one reference value;
- for location where said comparing indicates an undesired image moiré artifact, adjusting a color pixel defined by said plural separations to limit three color moiré.
Dependencies are inferred from the claim text.