Raster image processor with printhead profile compensation for a multi level digital printing machine
First Claim
1. A method of generating a screened multi-bit data output file for a digital printing machine having first and second nozzles that each can print on a page a first printable tone level, a second printable tone level, and a third printable tone level, from an unscreened raster data file specifying a continuous tone value for a first colorant for each printable position of the page, the method comprising the steps of:
- (a) creating a first printer profile comprising density measurements for the first colorant from the first nozzle;
(b) creating a first set of tonal sub-ranges based upon said first printer profile of the first nozzle;
said first set of tonal sub-ranges comprising first and second tonal sub-ranges corresponding to the first and second printable tone levels, respectively, for the first colorant;
(c) creating a second printer profile comprising density measurements for the first colorant from the second nozzle that are different that the density measurements of the first printer profile; and
(d) creating a second set of tonal sub-ranges based upon said second printer profile of the second nozzle;
said second set of tonal sub-ranges comprising first and second tonal sub-ranges corresponding to the first and second printable tone levels, respectively, for the first colorant.
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Accused Products
Abstract
System and method of calibration, screening, and compensation for multiple gray-level digital presses. Unequal quantization of the input range is employed with compensated overlapping of sub-ranges. Multiple instances of bi-level screening algorithms, tone modification functions, and a recombination algorithm are employed to produce calibrated screening on individual tone ranges. The method works with any bi-level screening algorithm and devices with any number of gray-levels. Quality imaging results from high detail, high tonal accuracy, low screening noise, and lack of printed artifacts. Dynamic re-calibration is facilitated. The elimination of the constraint of evenly spaced gray-levels has advantages of cost and yield for print head fabricators and digital press manufacturers. Multiple implementations are given for hardware and software embodiments. The present invention, which comprises a print profile for each colorant, is extended to comprise additional print profiles, as needed, specifying the print characteristic of a single or group of aberrant nozzles.
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Citations
24 Claims
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1. A method of generating a screened multi-bit data output file for a digital printing machine having first and second nozzles that each can print on a page a first printable tone level, a second printable tone level, and a third printable tone level, from an unscreened raster data file specifying a continuous tone value for a first colorant for each printable position of the page, the method comprising the steps of:
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(a) creating a first printer profile comprising density measurements for the first colorant from the first nozzle; (b) creating a first set of tonal sub-ranges based upon said first printer profile of the first nozzle;
said first set of tonal sub-ranges comprising first and second tonal sub-ranges corresponding to the first and second printable tone levels, respectively, for the first colorant;(c) creating a second printer profile comprising density measurements for the first colorant from the second nozzle that are different that the density measurements of the first printer profile; and (d) creating a second set of tonal sub-ranges based upon said second printer profile of the second nozzle;
said second set of tonal sub-ranges comprising first and second tonal sub-ranges corresponding to the first and second printable tone levels, respectively, for the first colorant. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method of generating a screened multi-bit data file for a digital printing machine that can print on a page a first printable level, a second printable level, and a third printable level, from an unscreened raster data file specifying a continuous tone value for a first colorant for each printable position of the page, the method comprising the steps of:
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providing a first tonal sub-range corresponding substantially to increasing percentages of the first printable level for the first colorant;
each of said first tonal sub-range comprises a beginning boundary value and an ending boundary valueproviding a second tonal sub-range corresponding substantially to increasing percentages of the second printable tone level for the first colorant;
said second tonal sub-range comprises a beginning boundary value and an ending boundary valueproviding a third tonal sub-range corresponding substantially to increasing percentages of the third printable tone level for the first colorant;
said third tonal sub-range comprises a beginning boundary value and an ending boundary value; andsetting the size of the first tonal sub-range based on the density of the first printable level printed by the digital printing machine. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14, 15)
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16. A raster image processor for generating a screened multi-bit data file for a digital printing machine that can print on a page a first printable level, a second printable level, and a third printable level, from an unscreened raster data file specifying a continuous tone value for a first colorant for each printable position of the page, the raster image processor comprises:
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a tone sub-range module comprises a first set of computer instructions to create a first tonal sub-range corresponding substantially to increasing percentages of the first printable level for the first colorant;
a second set of instructions to create a second tonal sub-range corresponding substantially to increasing percentages of the second printable tone level for the first colorant; and
a third set of instructions to create a third tonal sub-range corresponding substantially to increasing percentages of the third printable tone level for the first colorant;
each of said first, second, and third tonal sub-ranges comprise a beginning and ending boundary value; anda shifting module comprises a first set of computer instructions to set the size of said first tonal sub-range based on the density of the first printable level printed by the digital printing machine. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24)
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Specification