Method and apparatus for reducing marking material coverage in printing processes

Claim 2

A method as claimed in claim 1, wherein the step of processing the binary signals forming the input image to reduce the number of first binary signals in the input image in regions therein adjacent to edges corresponding to the edge mapping signal includes the substeps of: measuring ink coverage in the area adjacent to the edge; selecting an amount of reduction of the corresponding number of first binary signals in regions adjacent to edges in the input image by an amount related to the ink coverage.

Claim 3

A method as claimed in claim 1 or claim 2, including: processing the binary signals to form a multibit signal therefrom approximating a continuous tone image; and operating on the multibit signals to detect the edges.

Claim 5

A method as claimed in claim 3 or claim 4, wherein the step of processing the binary signals to form a multibit signal therefrom approximating a continuous tone image, operates on a plurality of binary signals to average the binary signals over a small area of the image.

Claim 6

A method as claimed in claim 5, wherein for each binary image signal, a corresponding continuous tone image multibit signal is generated, by averaging binary image signals in a 3 x 3 neighborhood surrounding the binary image signal for which a continuous tone image multibit signal is to be generated.

Claim 7

A method as claimed in claim 4, wherein the step of processing the binary signals from the multiple separations to determine, within an image whether coverage reduction at a detected edge is required, and producing a separation correlation signal therefrom includes the substep of: identifying a given area in the color document image; determining whether binary signals having a first state are present in at least one separation in at least a preselected set of locations within said given area; producing said separation correlation signal responsive to said determining substep.

Claim 8

An image processing device for processing a color document image for printing with an ink jet printer, to reduce an amount of marking material used to reproduce image edge regions therein on a receiving medium, the color document image comprised of multiple separations each defined by image signals arranged in an array of scan lines, including the steps of: a signal input, receiving electronic binary signals forming a multiple separation of the input image, in which the binary signals are suitable for driving an ink jet printer to deposit a separation color of ink on a receiving medium, where binary signals having a first binary state cause the ink jet printer to deposit the separation color of ink on the receiving medium and signals having a second binary state cause the ink jet printer not to deposit the separation color of ink on the receiving medium; means for processing the received binary signals to identify edges in the color document image and produce signals indicative of the location thereof; means for processing the received binary signals to reduce the number of binary signals having a first binary state, whereby ink coverage is reduced at identified edges in the image when printed, responsive to the edge identification signal; a processed image output, directing the coverage reduce binary signals to an ink jet printer.

Claim 9

An image processing device for processing a color document image for printing with an ink jet printer, to reduce an amount of marking material used to reproduce image edge regions therein on a receiving medium, the color document image comprised of multiple separations each defined by image signals arranged in an array of scan lines, including the steps of: a signal input, receiving electronic binary signals forming a multiple separation of the input image, in which the binary signals are suitable for driving an ink jet printer to deposit a separation color of ink on a receiving medium, where binary signals having a first binary state cause the ink jet printer to deposit the separation color of ink on the receiving medium and signals having a second binary state cause the ink jet printer not to deposit the separation color of ink on the receiving medium; a first filter, processing the received binary signals to form a multibit signal therefrom approximating a continuous tone image; an edge detecting circuit processing the multibit signal to detect edges, and generating an edge detection signal indicating locations of image edges in the input image; a separation correlation circuit processing received binary signals from the multiple separations to determine, within an image whether coverage reduction at a detected edge is required, and producing a separation correlation signal therefrom; a combining circuit, receiving as inputs the edge detection signal and the separation correlation circuit and combining said inputs to generate a corrected edge detection signal, indicating those edges at which coverage reduction will occur; an average measurement circuit, measuring coverage within a given area of the color document image; a tone reproduction curve processor, providing a lookup table in memory, and receiving as an input the binary signal value and the measured coverage value, and producing as an output a tone reproduction curve corrected signal; a masking arrangement, having as inputs the tone reproduction curve corrected signals and the corrected edge detection signals, and operable to mask the tone reproduction curve corrected signals with the correction edge detection signal to produce coverage reduced binary signals responsive thereto; a processed image output, directing the coverage reduced binary signals to an ink jet printer.

Claim 10

A device is claimed in claim 8 or claim 9, wherein said means to reduce the number of binary signals having a first binary state responsive to the edge identification signals, reduces the number of signals having a first binary state to zero at locations identified as edges.