Image processing for ink-jet printing with fast-and slow-drying inks

Claim 1

A method of printing an image based on digital data on a substrate, comprising the steps of: identifying from the digital data a subset of the digital data relating to a portion of the image wherein pixels associated with the digital data are of a predetermined spatial relationship with pixels intended to be of a different color as the pixels associated with the digital data, wherein the identifying step includes the steps of forming a first data stream comprising image data for pixels intended to be printed in a first preselected color, and a second data stream comprising image data for pixels intended to be printed in a second preselected color different from the first preselected color; polling data corresponding to proximal locations in the image based on the digital data in the first data stream and the second data stream; and identifying data in the first data stream as the subset of digital data when image data for pixels intended to be printed in the first preselected color on the first data stream are present with image data for pixels intended to be printed in the second preselected color on the second data stream; causing the subset of digital data to activate a printhead adapted to emit ink of a first type; and causing digital data not in the subset to activate a printhead adapted to emit ink of a second type, the ink of the first type being adapted to dry at a faster rate than the ink of the second type.

Claim 2

A method of printing an image based on digital data on a substrate, comprising the steps of: identifying from the digital data a subset of the digital data relating to a portion of the image wherein pixels associated with the digital data are of a predetermined spatial relationship with pixels intended to be of a different color as the pixels associated with the digital data, wherein the identifying step includes the steps of forming a first data stream comprising image data for pixels intended to be printed in a first preselected color, and a second data stream comprising image data for pixels intended to be printed in a second preselected color different from the first preselected color; polling data corresponding to proximal locations in the image based on the digital data in the first data stream and the second data stream; and identifying data in the first data stream as the subset of digital data when image data for pixels intended to be printed in the first preselected color on the first data stream are present with image data for pixels intended to be printed in the second preselected color on the second data stream; causing the subset of digital data to activate a printhead adapted to emit ink of a first type; and causing digital data not in the subset to activate a printhead adapted to emit ink of a second type, the ink of the first type being adapted to dry at a faster rate than the ink of the second type.

Claim 7

A method of printing an image based on digital data on a substrate, comprising the steps of: identifying from the digital data a subset of the digital data relating to a portion of the image wherein pixels associated with the digital data are of a predetermined spatial relationship with pixels intended to be of a different color as the pixels associated with the digital data, wherein the identifying step includes the step of identifying from the digital data a subset of the digital data relating to a halftone pattern, and wherein the step of identifying from the digital data a subset of the digital data relating to a halftone pattern includes the steps of comparing, for each pixel in the image, said pixel to each of neighboring pixels to determine whether it is a local area minimum or maximum; deriving, from said determination step, two image signals, a first image signal representing local area maximums of the image, and a second image signal representing local area minimums of the image; measuring image density over a block of pixels with respect to a reference value; auto correlating the first image signal if measured image density is relatively high with respect to the reference, or auto correlating the second image signal if measured image density is relatively low with respect to the reference value; evaluating the auto correlation over the block of pixels for each of a plurality of offset values selected as corresponding to probable halftone frequencies; determining, from the auto correlated signal, for each offset value whether the result of the auto correlation evaluation is a zero or non-zero value, the presence of a non-zero value indicating the presence of halftone images at the frequency corresponding to the offset value; and identifying the pixels being associated with the halftone images at the frequency corresponding to the offset value as belonging to the subset of digital data; causing the subset of digital data to activate a printhead adapted to emit ink of a first type; and causing non-subset digital data to activate a printhead adapted to emit ink of a second type, the ink of the first type being adapted to dry at a faster rate than the ink of the second type.

Claim 8

A method of printing an image based on digital data on a substrate, comprising the steps of: identifying from the digital data a subset of the digital data relating to a portion of the image wherein pixels associated with the digital data are of a predetermined spatial relationship with pixels intended to be of a different color as the pixels associated with the digital data, wherein the identifying step includes the step of identifying from the digital data a subset of the digital data relating to a halftone pattern, and wherein the step of identifying from the digital data a subset of the digital data relating to a halftone pattern includes the steps of comparing, for each pixel in the image, said pixel to each of neighboring pixels to determine whether it is a local area minimum or maximum; deriving, from said determination step, two image signals, a first image signal representing local area maximums of the image, and a second image signal representing local area minimums of the image; measuring image density over a block of pixels with respect to a reference value; auto correlating the first image signal if measured image density is relatively high with respect to the reference, or auto correlating the second image signal if measured image density is relatively low with respect to the reference value; evaluating the auto correlation over the block of pixels for each of a plurality of offset values selected as corresponding to probable halftone frequencies; determining, from the auto correlated signal, for each offset value whether the result of the auto correlation evaluation is a zero or non-zero value, the presence of a non-zero value indicating the presence of halftone images at the frequency corresponding to the offset value; and identifying the pixels being associated with the halftone images at the frequency corresponding to the offset value as belonging to the subset of digital data; causing the subset of digital data to activate a printhead adapted to emit ink of a first type; and causing non-subset digital data to activate a printhead adapted to emit ink of a second type, the ink of the first type being adapted to dry at a faster rate than the ink of the second type.