Apparatus for subsampling chrominance

Claim 3

Am apparatus for sensing and subsampling luminance and chrominance of features on an object being scanned in a fast scan direction and a slow scan direction, comprising: an array of n subsampling sensor sets spanning a fast scan direction width of n times m pixels, each of said sensor sets including, aligned in a slow scan direction column, a set of m pixel-sized green sensors aligned in a fast scan direction line for determining pixel-by-pixel green color and luminance, a red sensor extending m pixels wide in said fast scan direction and m pixels long in said slow scan direction for detecting red color, and a blue sensor extending m pixels wide in said fast scan direction and m pixels long in said slow scan direction for detecting blue color; and a main processor for determining a high resolution luminance according to a luminance output of said green sensors whereby said luminance outputs are transformed into Y tristimulus values and thereafter to high resolution L* values corresponding to the features of the object and a low resolution subsampled chrominance output according to said red sensor and said blue sensor color determinations, whereby said luminance and chrominance outputs are transformed into X, Y and Z tristimulus values and thereafter to color corrected L*, a* and b* values corresponding to the features of the object, wherein the main processor comprises a pretransformation chrominance channel summing processor for increasing a chrominance output precision, and a pretransformation luminance channel summing processor for increasing a luminance output precision and wherein said chrominance channel summing processor sums a quantity m of red color detections from said red sensors and m blue color detections from said blue sensors, and wherein said luminance channel summing processor sums 2 times m green sensor detections of luminance from said green sensors.

Claim 4

Am apparatus for sensing and subsampling luminance and chrominance of features on an object being scanned in a fast scan direction and a slow scan direction, comprising: an array of n subsampling sensor sets spanning a fast scan direction width of n times m pixels, each of said sensor sets including, aligned in a slow scan direction column, a set of m pixel-sized green sensors aligned in a fast scan direction line for determining pixel-by-pixel green color and luminance, a red sensor extending m pixels wide in said fast scan direction and m pixels long in said slow scan direction for detecting red color, and a blue sensor extending m pixels wide in said fast scan direction and m pixels long in said slow scan direction for detecting blue color; and a main processor for determining a high resolution luminance according to a luminance output of said green sensors whereby said luminance outputs are transformed into Y tristimulus values and thereafter to high resolution L* values corresponding to the features of the object and a low resolution subsampled chrominance output according to said red sensor and said blue sensor color determinations, whereby said luminance and chrominance outputs are transformed into X, Y and Z tristimulus values and thereafter to color corrected L*, a* and b* values corresponding to the features of the object, wherein the main processor comprises a pretransformation chrominance channel summing processor for increasing a chrominance output precision, and a pretransformation luminance channel summing processor for increasing a luminance output precision and wherein said chrominance channel summing processor sums a quantity m of red color detections from said red sensors and m blue color detections from said blue sensors, and wherein said luminance channel summing processor sums 2 times m green sensor detections of luminance from said green sensors.

Claim 7

An electrophotographic printing machine having an apparatus for sensing and subsampling luminance and chrominance of a sheet having multicolored indicia thereon, and means responsive to L* a* and b* values for reproducing a copy of the sheet being scanned in a fast scan direction and a slow scan directing, said apparatus comprising: an array of n subsampling sensor sets spanning a fast scan direction width of n times m pixels, each of said sensor sets including, aligned in a slow scan direction column, a set of 2 pixel-sized green sensors aligned in a fast scan direction line for determining pixel-by-pixel green color and luminance, a red sensor extending 2 pixels wide in said fast scan direction and 2 pixels long in said slow scan direction for detecting red color, and a blue sensor extending 2 pixels wide in said fast scan direction and 2 pixels long in said slow scan direction for detecting blue color; and a main processor for determining a high resolution luminance according to a luminance output of said green sensors whereby said luminance outputs are transformed into Y tristimulus values and thereafter to high resolution L* values corresponding to the multicolored indicia on the sheet and a low resolution subsampled chrominance output according to said red sensor and said blue Sensor color determinations whereby said luminance and chrominance outputs are transformed into X, Y and Z tristimulus values and thereafter to color corrected L* a* and b* values corresponding to the multicolored indicia on the sheet, wherein said red sensor and said blue sensor outputs are multiplexed for transmission on a chrominance channel prior to transformation into the x, Y and Z tristimulus values and wherein said green sensor outputs are transmitted on a luminance channel and wherein said main processor comprises a first pretransformation dual output analog to digital converter for receiving analog voltage inputs from the chrominance channel, and a second pretransformation dual output analog to digital converter for receiving analog voltage inputs from the luminance channel, whereby each converter provides digital outputs according to a first ratio of corresponding analog inputs up to a preselected voltage input value and whereby each converter provides the digital outputs according to a second ratio of corresponding analog inputs above the preselected voltage input value.

Claim 8

An electrophotographic printing machine having an apparatus for sensing and subsampling luminance and chrominance of a sheet having multicolored indicia thereon, and means responsive to L* a* and b* values for reproducing a copy of the sheet being scanned in a fast scan direction and a slow scan directing, said apparatus comprising: an array of n subsampling sensor sets spanning a fast scan direction width of n times m pixels, each of said sensor sets including, aligned in a slow scan direction column, a set of 2 pixel-sized green sensors aligned in a fast scan direction line for determining pixel-by-pixel green color and luminance, a red sensor extending 2 pixels wide in said fast scan direction and 2 pixels long in said slow scan direction for detecting red color, and a blue sensor extending 2 pixels wide in said fast scan direction and 2 pixels long in said slow scan direction for detecting blue color; and a main processor for determining a high resolution luminance according to a luminance output of said green sensors whereby said luminance outputs are transformed into Y tristimulus values and thereafter to high resolution L* values corresponding to the multicolored indicia on the sheet and a low resolution subsampled chrominance output according to said red sensor and said blue Sensor color determinations whereby said luminance and chrominance outputs are transformed into X, Y and Z tristimulus values and thereafter to color corrected L* a* and b* values corresponding to the multicolored indicia on the sheet, wherein said red sensor and said blue sensor outputs are multiplexed for transmission on a chrominance channel prior to transformation into the x, Y and Z tristimulus values and wherein said green sensor outputs are transmitted on a luminance channel and wherein said main processor comprises a first pretransformation dual output analog to digital converter for receiving analog voltage inputs from the chrominance channel, and a second pretransformation dual output analog to digital converter for receiving analog voltage inputs from the luminance channel, whereby each converter provides digital outputs according to a first ratio of corresponding analog inputs up to a preselected voltage input value and whereby each converter provides the digital outputs according to a second ratio of corresponding analog inputs above the preselected voltage input value.

Claim 9

An electrophotographic printing machine having an apparatus for sensing and subsampling luminance and chrominance of a sheet having multicolored indicia thereon, and means responsive to L* a* and b* values for reproducing a copy of the sheet being scanned in a fast scan direction and a slow scan direction, said apparatus comprising: an array of n subsampling sensor sets spanning a fast scan direction width of n times m pixels, each of said sensor sets including, aligned in a slow scan direction column, a set of 2 pixel-sized green sensors aligned in a fast scan direction line for determining pixel-by-pixel green color and luminance, a red sensor extending 2 pixels wide in said fast scan direction and 2 pixels long in said slow scan direction for detecting red color, and a blue sensor extending 2 pixels wide in said fast scan direction and 2 pixels long in said slow scan direction for detecting blue color, and a main processor for determining a high resolution luminance according to a luminance output of said green sensors whereby said luminance outputs are transformed into Y tristimulus values and thereafter to high resolution L* values corresponding to the multicolored indicia on the sheet and a low resolution subsampled chrominance output according to said red sensor and said blue sensor color determinations whereby said luminance and chrominance outputs are transformed into X, Y and Z tristimulus values and thereafter to color corrected L* a* and b* values corresponding to the multicolored indicia on the sheet, wherein the main processor comprises a pretransformation chrominance channel summing processor for increasing a chrominance output precision, and a pretransformation luminance channel summing processor for increasing a luminance output precision and wherein said chrominance channel summing processor sums a quantity 2 of red color detections from said red sensors and 2 blue color detections from said blue sensors, and wherein said luminance channel summing processor sums 2 times 2 green sensor detections of luminance from said green sensors.

Claim 10

An electrophotographic printing machine having an apparatus for sensing and subsampling luminance and chrominance of a sheet having multicolored indicia thereon, and means responsive to L* a* and b* values for reproducing a copy of the sheet being scanned in a fast scan direction and a slow scan direction, said apparatus comprising: an array of n subsampling sensor sets spanning a fast scan direction width of n times m pixels, each of said sensor sets including, aligned in a slow scan direction column, a set of 2 pixel-sized green sensors aligned in a fast scan direction line for determining pixel-by-pixel green color and luminance, a red sensor extending 2 pixels wide in said fast scan direction and 2 pixels long in said slow scan direction for detecting red color, and a blue sensor extending 2 pixels wide in said fast scan direction and 2 pixels long in said slow scan direction for detecting blue color, and a main processor for determining a high resolution luminance according to a luminance output of said green sensors whereby said luminance outputs are transformed into Y tristimulus values and thereafter to high resolution L* values corresponding to the multicolored indicia on the sheet and a low resolution subsampled chrominance output according to said red sensor and said blue sensor color determinations whereby said luminance and chrominance outputs are transformed into X, Y and Z tristimulus values and thereafter to color corrected L* a* and b* values corresponding to the multicolored indicia on the sheet, wherein the main processor comprises a pretransformation chrominance channel summing processor for increasing a chrominance output precision, and a pretransformation luminance channel summing processor for increasing a luminance output precision and wherein said chrominance channel summing processor sums a quantity 2 of red color detections from said red sensors and 2 blue color detections from said blue sensors, and wherein said luminance channel summing processor sums 2 times 2 green sensor detections of luminance from said green sensors.