Method for calibrating a color marking engine for halftone operation
First Claim
1. A method of calibrating the half-tone operation of a color marking engine for creating half-tone images formed in bi-level or quad-level dot density formats, comprising the steps of:
- running a test pattern on each of one or more color marking engines to provide an output image of a plurality of gray patches formed of first, second and third color toners associated with the color marking engine wherein the gray patches include first, second and third sets of patches reproduced respectively at dot density levels of 25%, 50% and 75% of a maximum dot density and wherein relative color toner levels in the gray patches within each first, second and third set of patches vary a predetermined increment in value above or below the toner levels in a median valued gray patch;
visually selecting an output image of a selected color marking engine having a minimum of color shift associated therewith in accordance with predetermined visual criteria;
determining a correction factor defined for each color at the maximum dot density; and
storing the correction factor as an offset maximum density for images created at the bi-level and quad-level formats.
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Abstract
A method is disclosed for calibrating the half-tone operation of a color marking engine for creating images formed in bi-level or quad-level dot density formats. In the first step, a test pattern is run to provide an output image of a plurality of gray patches formed of first, second and third color toners. The gray patches of the output image include first, second and third sets of patches reproduced respectively at dot density levels of 25%, 50% and 75% of a maximum dot density. The relative color toner levels in the gray patches within each set of patches varies a predetermined increment in value above or below the toner levels in a median valued gray patch. The remaining steps of the method include visually selecting an output image of a selected color marking engine having a minimum color shift; determining a correction factor defined for each color at the maximum dot density; and storing the correction factor as an offset from maximum density for images created at the bi-level and quad-level formats.
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Citations
20 Claims
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1. A method of calibrating the half-tone operation of a color marking engine for creating half-tone images formed in bi-level or quad-level dot density formats, comprising the steps of:
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running a test pattern on each of one or more color marking engines to provide an output image of a plurality of gray patches formed of first, second and third color toners associated with the color marking engine wherein the gray patches include first, second and third sets of patches reproduced respectively at dot density levels of 25%, 50% and 75% of a maximum dot density and wherein relative color toner levels in the gray patches within each first, second and third set of patches vary a predetermined increment in value above or below the toner levels in a median valued gray patch;
visually selecting an output image of a selected color marking engine having a minimum of color shift associated therewith in accordance with predetermined visual criteria;
determining a correction factor defined for each color at the maximum dot density; and
storing the correction factor as an offset maximum density for images created at the bi-level and quad-level formats. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. An apparatus for calibrating the half-tone operation of a color marking engine for creating images formed in bi-level or quad-level dot density formats, comprising:
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at least one color marking engine operable for creating half-tone images formed in bi-level or quad-level dot density formats;
a test pattern for running on each color marking engine to provide an output image of a plurality of gray patches formed of first, second and third color toners associated with said color marking engine wherein said gray patches include first, second and third sets of patches reproduced respectively at dot density levels of 25%, 50% and 75% of a maximum density and wherein relative color toner levels in said gray patches within each said first, second and third sets of patches vary a predetermined increment in value above or below said toner levels in a median valued gray patch;
an output of each selected color marking engine, which is operable to provide said output image whereby said output image may be visually selected for having a minimum of color shift associated therewith in accordance with predetermined visual criteria; and
a memory for storing a correction factor, determined for each color and defined at a maximum dot density thereof, said correction factor corresponding to an offset value from said maximum dot density for output images created at said bi-level and quad-level formats. - View Dependent Claims (15, 16, 17, 18, 19, 20)
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Specification