Online grey balance with dynamic highlight and shadow controls
AssigneeXerox Corporation
InventorsR. Viturro, Lalit Mestha
Life of this patent
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Abstract
Tone reduction curves are utilized to map an input value to an output value. A tone reduction curve is normally produced by an algorithm that fits a curve to a series of knots. Knots can be determined from calibration data. Printing a calibration patch pattern yields a target patch pattern. The desired reflectances of the calibration patches and the measured reflectances of target patches can be used as calibration data. The series of knots can also include a highlight knot and a shadow knots so that the tone reduction curve functions better in the highlight and shadow regions.
Claims20
A method comprising:
- producing a target patch pattern by printing a calibration patch pattern on a substrate wherein said calibration patch pattern comprises at least two calibration patches that are developable and have at least two desired reflectances;
- measuring said target patch pattern to obtain at least two target reflectances;
- and
- determining a target highlight value from calibration data comprising an input highlight value, said at least two target reflectances and said at least two desired reflectances, thereby obtaining a target highlight value in a less developable region.
A method comprising:
- obtaining calibration data comprising at least one target saturation and at least one maximum desired saturation;
- using said calibration data to produce a tone reproduction curve, thereby setting said tone reproduction curve for use in printing saturated areas.
A system comprising:
- a storage device adapted to store a calibration patch pattern comprising at least two calibration patches;
- a marking engine that marks a substrate based on said calibration patch pattern to produce a target patch pattern;
- a color measuring device that obtains at least two target reflectances from said target patch pattern;
- a processor that determines at least one target highlight value and at least one tone reproduction curve from calibration data comprising an input highlight value and said at least two target reflectances;
- a second storage device adapted to store said at least one tone reproduction curve.
Dependencies are inferred from the claim text.