Image processing method to reduce marking material coverage in printing processes

Claim 1

A method for processing a color image for printing to reduce an amount of marking material used therefor, the color image comprised of multiple separations each defined by a bitmap of single bit pixels each having a pixel value and arranged in an array of scan lines, including the steps of: for each separation bitmap, measuring a marking material coverage value over a given area within the image, directing pixel values of a set of k pixels from a single scan line of pixels into a latch, where k is an integer number of pixels, providing a pre-loaded look up table, having a set of k bit addresses, each address corresponding to data entries including a possible combination of marking material coverage values for a set of k pixels, storing to a memory, the marking material coverage values from the look up table corresponding to each set of k pixel values for a set of l scan lines, and summing for the image, the marking material coverage values for each separation over the area of a set of k pixel values in a set of l scan lines; summing the measured marking material coverage of each separation bitmap to determine measured marking material coverage for the color image; comparing desired marking material coverage with measured marking material coverage to derive an ON/OFF ratio, where the ON/OFF ratio represents a fraction of pixels to be turned OFF, compared to the number of pixels in the given area of the separation; randomly setting a fraction of pixels to OFF in the given area of the separation bitmap, in accordance with the turn OFF ratio; and outputting the separation bitmap to a print controller.

Claim 2

A method for processing a color image for printing to reduce an amount of marking material used therefor, the color image comprised of multiple separations each defined by a bitmap of single bit pixels each having a pixel value and arranged in an array of scan lines, including the steps of: for each separation bitmap, measuring a marking material coverage value over a given area within the image, directing pixel values of a set of k pixels from a single scan line of pixels into a latch, where k is an integer number of pixels, providing a pre-loaded look up table, having a set of k bit addresses, each address corresponding to data entries including a possible combination of marking material coverage values for a set of k pixels, storing to a memory, the marking material coverage values from the look up table corresponding to each set of k pixel values for a set of l scan lines, and summing for the image, the marking material coverage values for each separation over the area of a set of k pixel values in a set of l scan lines; summing the measured marking material coverage of each separation bitmap to determine measured marking material coverage for the color image; comparing desired marking material coverage with measured marking material coverage to derive an ON/OFF ratio, where the ON/OFF ratio represents a fraction of pixels to be turned OFF, compared to the number of pixels in the given area of the separation; randomly setting a fraction of pixels to OFF in the given area of the separation bitmap, in accordance with the turn OFF ratio; and outputting the separation bitmap to a print controller.

Claim 3

A method for processing a color image for printing to reduce an amount of marking material used therefor, the color image comprised of multiple separations each defined by a bitmap of single bit pixels each having a pixel value and arranged in an array of scan lines, including the steps of: for each separation bitmap, measuring a marking material coverage value over a given area within the image; summing the measured marking material coverage of each separation bitmap to determine measured marking material coverage for the color image; comparing desired marking material coverage with measured marking material coverage to derive an ON/OFF ratio, where the ON/OFF ratio represents a fraction of pixels to be turned OFF, compared to the number of pixels in the given area of the separation; randomly setting a fraction of pixels to OFF in the given area of the separation bitmap, in accordance with the turn OFF ratio and incrementing a counter value by a predetermined amount related to the OFF/ON ratio, whereby increasing the counter value increases the likelihood of the pixel being set OFF; comparing the counter value with a random value to determine whether to set the pixel OFF; upon determining that a pixel should be turned OFF, resetting the counter so that the next pixel has a decreased probability of being turned OFF; logically processing the pixel value and the ON/OFF determination to determine the separation bitmap to be output; and outputting the separation bitmap to a print controller.

Claim 4

A method for processing a color image for printing to reduce an amount of marking material used therefor, the color image comprised of multiple separations each defined by a bitmap of single bit pixels each having a pixel value and arranged in an array of scan lines, including the steps of: for each separation bitmap, measuring a marking material coverage value over a given area within the image; summing the measured marking material coverage of each separation bitmap to determine measured marking material coverage for the color image; comparing desired marking material coverage with measured marking material coverage to derive an ON/OFF ratio, where the ON/OFF ratio represents a fraction of pixels to be turned OFF, compared to the number of pixels in the given area of the separation; randomly setting a fraction of pixels to OFF in the given area of the separation bitmap, in accordance with the turn OFF ratio and incrementing a counter value by a predetermined amount related to the OFF/ON ratio, whereby increasing the counter value increases the likelihood of the pixel being set OFF; comparing the counter value with a random value to determine whether to set the pixel OFF; upon determining that a pixel should be turned OFF, resetting the counter so that the next pixel has a decreased probability of being turned OFF; logically processing the pixel value and the ON/OFF determination to determine the separation bitmap to be output; and outputting the separation bitmap to a print controller.

Claim 5

A method for processing a color image for printing to reduce an amount of marking material used therefor, the color image comprised of multiple separations each defined by a bitmap of single bit pixels each having a pixel value and arranged in an array of scan lines, including the steps of: for each separation bitmap, measuring a marking material coverage value over a given area within the image; summing the measured marking material coverage of each separation bitmap to determine measured marking material coverage for the color image; comparing desired marking material coverage with measured marking material coverage to derive an ON/OFF ratio, where the ON/OFF ratio represents a fraction of pixels to be turned OFF, compared to the number of pixels in the given area of the separation, and determining the location in the image of pixels which should be turned off in accordance with the turn off ratio; randomly setting a fraction of pixels to OFF in the given area of the separation bitmap, in accordance with the turn OFF ratio; and outputting the separation bitmap to a print controller.

Claim 6

A method for processing a color image for printing to reduce an amount of marking material used therefor, the color image comprised of multiple separations each defined by a bitmap of single bit pixels each having a pixel value and arranged in an array of scan lines, including the steps of: for each separation bitmap, measuring a marking material coverage value over a given area within the image; summing the measured marking material coverage of each separation bitmap to determine measured marking material coverage for the color image; comparing desired marking material coverage with measured marking material coverage to derive an ON/OFF ratio, where the ON/OFF ratio represents a fraction of pixels to be turned OFF, compared to the number of pixels in the given area of the separation, and determining the location in the image of pixels which should be turned off in accordance with the turn off ratio; randomly setting a fraction of pixels to OFF in the given area of the separation bitmap, in accordance with the turn OFF ratio; and outputting the separation bitmap to a print controller.

Claim 10

A method for processing a color image for printing by an ink jet printer to reduce ink used thereby, the color image comprised of multiple separations each defined by a bitmap of single bit pixels each having a pixel value and arranged in an array of scan lines, including the steps of: for each separation bitmap, measuring an ink coverage value over a given area within the image and summing the ink coverage of each bitmap to determine total ink coverage including: directing pixel values of a set of k pixels from a single scan line of pixels into a latch, where k is an integer number of pixels, providing a pre-loaded look up table, having a set of k bit addresses, each address corresponding to data entries including a possible combination of ink coverage values for a set of k pixels, storing to a memory, the ink coverage values from the look up table corresponding to each set of k pixel values for a set of l scan lines, and summing for the image, the ink coverage values for each separation over the area of a set of k pixel values in a set of l scan lines; comparing desired ink coverage with measured total ink coverage to derive an ON/OFF ratio, where the ON/OFF ratio represents a fraction of pixels to be turned OFF, compared to the number of pixels in the separation; randomly setting a fraction of pixels to OFF in the given area of the separation bitmap in a larger number of pixels in the separation, in accordance with the turn OFF ratio; and outputting the separation bitmap to a print controller.

Claim 11

A method for processing a color image for printing by an ink jet printer to reduce ink used thereby, the color image comprised of multiple separations each defined by a bitmap of single bit pixels each having a pixel value and arranged in an array of scan lines, including the steps of: for each separation bitmap, measuring an ink coverage value over a given area within the image and summing the ink coverage of each bitmap to determine total ink coverage including: directing pixel values of a set of k pixels from a single scan line of pixels into a latch, where k is an integer number of pixels, providing a pre-loaded look up table, having a set of k bit addresses, each address corresponding to data entries including a possible combination of ink coverage values for a set of k pixels, storing to a memory, the ink coverage values from the look up table corresponding to each set of k pixel values for a set of l scan lines, and summing for the image, the ink coverage values for each separation over the area of a set of k pixel values in a set of l scan lines; comparing desired ink coverage with measured total ink coverage to derive an ON/OFF ratio, where the ON/OFF ratio represents a fraction of pixels to be turned OFF, compared to the number of pixels in the separation; randomly setting a fraction of pixels to OFF in the given area of the separation bitmap in a larger number of pixels in the separation, in accordance with the turn OFF ratio; and outputting the separation bitmap to a print controller.

Claim 12

A method for processing a color image for printing by an ink let printer to reduce ink used thereby, the color image comprised of multiple separations each defined by a bitmap of single bit pixels each having a pixel value and arranged in an array of scan lines, including the steps of: for each separation bitmap, measuring an ink coverage value over a given area within the image and summing the ink coverage of each bitmap to determine total ink coverage; comparing desired ink coverage with measured total ink coverage to derive an ON/OFF ratio, where the ON/OFF ratio represents a fraction of pixels to be turned OFF, compared to the number of pixels in a separation; randomly setting a fraction of pixels to OFF in the given area of the separation bitmap in a larger number of pixels in a separation, in accordance with the turn OFF ratio including: incrementing a counter value by a predetermined amount related to the OFF/ON ratio, whereby increasing the counter value increases the likelihood of the pixel being set OFF, comparing the counter value with a random value to determine whether to set the pixel OFF, upon determining that a pixel should be turned OFF, resetting the counter so that the next pixel has a decreased probability of being turned OFF, logically processing the pixel value and the ON/OFF determination to determine the separation bitmap to be output; and outputting the separation bitmap to a print controller.

Claim 13

A method for processing a color image for printing by an ink let printer to reduce ink used thereby, the color image comprised of multiple separations each defined by a bitmap of single bit pixels each having a pixel value and arranged in an array of scan lines, including the steps of: for each separation bitmap, measuring an ink coverage value over a given area within the image and summing the ink coverage of each bitmap to determine total ink coverage; comparing desired ink coverage with measured total ink coverage to derive an ON/OFF ratio, where the ON/OFF ratio represents a fraction of pixels to be turned OFF, compared to the number of pixels in a separation; randomly setting a fraction of pixels to OFF in the given area of the separation bitmap in a larger number of pixels in a separation, in accordance with the turn OFF ratio including: incrementing a counter value by a predetermined amount related to the OFF/ON ratio, whereby increasing the counter value increases the likelihood of the pixel being set OFF, comparing the counter value with a random value to determine whether to set the pixel OFF, upon determining that a pixel should be turned OFF, resetting the counter so that the next pixel has a decreased probability of being turned OFF, logically processing the pixel value and the ON/OFF determination to determine the separation bitmap to be output; and outputting the separation bitmap to a print controller.

Claim 14

A method for processing a color image for printing by an ink jet printer to reduce ink used thereby, the color image comprised of multiple separations each defined by a bitmap of single bit pixels each having a pixel value and arranged in an array of scan lines, including the steps of: for each separation bitmap, measuring an ink coverage value over a given area within the image and summing the ink coverage of each bitmap to determine total ink coverage; comparing desired ink coverage with measured total ink coverage to derive an ON/OFF ratio, where the ON/OFF ratio represents a fraction of pixels to be turned OFF, compared to the number of pixels in a separation and determining the location in the image of pixels which should be turned OFF in accordance with the turn off ratio; randomly setting a fraction of pixels to OFF in the given area of the separation bitmap in a larger number of pixels in the separation, in accordance with the turn OFF ratio; and outputting the separation bitmap to a print controller.

Claim 15

A method for processing a color image for printing by an ink jet printer to reduce ink used thereby, the color image comprised of multiple separations each defined by a bitmap of single bit pixels each having a pixel value and arranged in an array of scan lines, including the steps of: for each separation bitmap, measuring an ink coverage value over a given area within the image and summing the ink coverage of each bitmap to determine total ink coverage; comparing desired ink coverage with measured total ink coverage to derive an ON/OFF ratio, where the ON/OFF ratio represents a fraction of pixels to be turned OFF, compared to the number of pixels in a separation and determining the location in the image of pixels which should be turned OFF in accordance with the turn off ratio; randomly setting a fraction of pixels to OFF in the given area of the separation bitmap in a larger number of pixels in the separation, in accordance with the turn OFF ratio; and outputting the separation bitmap to a print controller.

Claim 19

A method for processing a color image for printing, to reduce an amount of marking material used thereby, the color image comprised of multiple separations each defined by a bitmap of single bit pixels each having a pixel value and arranged in an array of scan lines, including the steps of: directing pixel values of a set of k pixels from a single scan line of pixels into a latch, where k is an integer number of pixels; providing a pre-loaded look up table, having a set of k bit addresses, each address corresponding to data entries including a possible combination of marking material coverage values for a set of k pixels; storing to a memory, the marking material coverage value from the look up table corresponding to each set of k pixel values for a set of l scan lines; summing the marking material coverage values for the set of l scan lines to derive a marking material coverage value for the area of k pixels by l scan lines in each separation; summing the marking material coverage values for the separations to derive a marking material coverage value for the image over an area of K pixels by l scan lines; determining the location in the image of pixels which should be turned OFF in accordance with the turn OFF ratio; incrementing a counter value by a predetermined amount related to the turn OFF ratio, whereby increasing the counter value increases the likelihood of the pixel being set OFF; comparing the counter value with a random value to determine whether to set the pixel OFF; upon determining that a pixel should be turned OFF, resetting the counter so that the next pixel has a decreased probability of being turned OFF; logically processing the pixel value and the ON/OFF determination to determine the separation bitmap to be output; and outputting each separation bitmap so processed to a printer.

Claim 20

A method for processing a color image for printing, to reduce an amount of marking material used thereby, the color image comprised of multiple separations each defined by a bitmap of single bit pixels each having a pixel value and arranged in an array of scan lines, including the steps of: directing pixel values of a set of k pixels from a single scan line of pixels into a latch, where k is an integer number of pixels; providing a pre-loaded look up table, having a set of k bit addresses, each address corresponding to data entries including a possible combination of marking material coverage values for a set of k pixels; storing to a memory, the marking material coverage value from the look up table corresponding to each set of k pixel values for a set of l scan lines; summing the marking material coverage values for the set of l scan lines to derive a marking material coverage value for the area of k pixels by l scan lines in each separation; summing the marking material coverage values for the separations to derive a marking material coverage value for the image over an area of K pixels by l scan lines; determining the location in the image of pixels which should be turned OFF in accordance with the turn OFF ratio; incrementing a counter value by a predetermined amount related to the turn OFF ratio, whereby increasing the counter value increases the likelihood of the pixel being set OFF; comparing the counter value with a random value to determine whether to set the pixel OFF; upon determining that a pixel should be turned OFF, resetting the counter so that the next pixel has a decreased probability of being turned OFF; logically processing the pixel value and the ON/OFF determination to determine the separation bitmap to be output; and outputting each separation bitmap so processed to a printer.

Claim 24

A device for processing a color image comprised of multiple separations each defined by a bitmap of single bit pixels for printing, for the reduction of marking material used in the color image, including: means for predicting the marking material coverage of an area in the output image as a function of the input image; means for determining a ratio of pixels to be turned OFF, as a function of the desired marking material coverage and the predicted marking material coverage, said means performing the functions of: maintaining a count value incremented for each pixel processed by a predetermined amount related to the turn OFF ratio, whereby increasing the counter value increases the likelihood of the pixel being set OFF, comparing the count value with a random value to determine whether to set the pixel OFF, and resetting the counter so that the next pixel has a decreased probability of being turned OFF; locating means for determining in a separation of the image, locations of pixels which should be turned OFF in accordance with the turn OFF ratio; turn off determining means for determining whether a pixel should be turned OFF in accordance with the turn OFF ratio in accordance with a random number function; a masking function, having as inputs the pixel values in each separation and the turn OFF ratio determination from said turn OFF determining means, and having as an output a pixel value for a reduced marking material image; and output means for directing the separation bitmap to a print controller.

Claim 25

A device for processing a color image comprised of multiple separations each defined by a bitmap of single bit pixels for printing, for the reduction of marking material used in the color image, including: means for predicting the marking material coverage of an area in the output image as a function of the input image; means for determining a ratio of pixels to be turned OFF, as a function of the desired marking material coverage and the predicted marking material coverage, said means performing the functions of: maintaining a count value incremented for each pixel processed by a predetermined amount related to the turn OFF ratio, whereby increasing the counter value increases the likelihood of the pixel being set OFF, comparing the count value with a random value to determine whether to set the pixel OFF, and resetting the counter so that the next pixel has a decreased probability of being turned OFF; locating means for determining in a separation of the image, locations of pixels which should be turned OFF in accordance with the turn OFF ratio; turn off determining means for determining whether a pixel should be turned OFF in accordance with the turn OFF ratio in accordance with a random number function; a masking function, having as inputs the pixel values in each separation and the turn OFF ratio determination from said turn OFF determining means, and having as an output a pixel value for a reduced marking material image; and output means for directing the separation bitmap to a print controller.

Claim 26

A device for processing a color image comprised of multiple separations each defined by a bitmap of single bit pixels for printing, for the reduction of marking material used in the color image, including: means for predicting the marking material coverage of an area in the output image as a function of the input image; means for determining a ratio of pixels to be turned OFF, as a function of the desired marking material coverage and the predicted marking material coverage; locating means for determining in a separation of the image, locations of pixels which should be turned OFF in accordance with the turn OFF ratio; turn OFF determining means for determining whether a pixel should be turned OFF in accordance with the turn OFF ratio in accordance with a random number function, including means for comparing the state of corresponding pixels in each separation bitmap and upon detection of a concurrence of pixels turned OFF, turning at least one pixel ON; a masking function, having as inputs the pixel values in each separation and the turn OFF ratio determination from said turn OFF determining means, and having as an output a pixel value for a reduced marking material image; and output means for directing the separation bitmap to a print controller.

Claim 27

A device for processing a color image comprised of multiple separations each defined by a bitmap of single bit pixels for printing, for the reduction of marking material used in the color image, including: means for predicting the marking material coverage of an area in the output image as a function of the input image; means for determining a ratio of pixels to be turned OFF, as a function of the desired marking material coverage and the predicted marking material coverage; locating means for determining in a separation of the image, locations of pixels which should be turned OFF in accordance with the turn OFF ratio; turn OFF determining means for determining whether a pixel should be turned OFF in accordance with the turn OFF ratio in accordance with a random number function, including means for comparing the state of corresponding pixels in each separation bitmap and upon detection of a concurrence of pixels turned OFF, turning at least one pixel ON; a masking function, having as inputs the pixel values in each separation and the turn OFF ratio determination from said turn OFF determining means, and having as an output a pixel value for a reduced marking material image; and output means for directing the separation bitmap to a print controller.