System and method for profiling digital-image input devices
AssigneeEastman Kodak Company
InventorChristopher J. Edge
Life of this patent
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Abstract
In a system and a method for profiling a digital-image input device, profiling of the digital-image input device is performed based at least on an image of a color chart and an estimated illumination of the color chart generated by comparing illumination of device-dependent coordinate values for the image of the color chart with illumination of device-independent coordinate values of the color chart. Because the estimated illumination of the color chart is performed on data pertaining to the color chart, the present invention may generate a profile without reference to data pertaining to scenery in the image outside of the color chart. Consequently, the present invention may generate a profile irrespective of the relative exposure of the color chart with respect to other scenery in the image.
Claims21
A method for profiling a digital-image input device comprising:
- an image of a color chart on the digital input device;
- estimating an illumination of the color chart;
- generating a profile independent of a relative exposure of the color chart with respect to other portions of the image outside of the color chart;
- determining device-dependent coordinate values for the image of the color chart;
- linearly scaling device-independent coordinate values of the color chart based at least on a scaling factor;
- and
- calculating first parameters describing tone curves of the digital-image input device based at least on the linearly scaled device-independent coordinate values.
A method for generating a profile for a digital-image input device, the method comprising:
- capturing an image of a color chart with the digital-image input device, wherein the color chart comprises a plurality of color patches;
- determining device-dependent coordinate values of each of the plurality of color patches of the image;
- estimating an illumination of a brightest gray patch of the plurality of color patches based at least on the device-dependent coordinate values;
- linearly scaling device-independent coordinate values for each of the plurality of color patches based at least on the estimated illumination;
- generating the profile for the digital-image input device based at least on the linearly scaled device-independent coordinate values or a derivative thereof;
- and
- storing the profile in a computer-accessible memory.
A method for generating a profile for a digital-image input device, the method comprising:
- capturing an image of a color chart with the digital-image input device, wherein the color chart comprises a plurality of color patches;
- determining device-dependent coordinate values of each of the plurality of color patches of the image;
- estimating an illumination of a brightest gray patch of the plurality of color patches based at least on the device-dependent coordinate values;
- linearly scaling device-independent coordinate values for each of the plurality of color patches based at least on the estimated illumination;
- calculating first parameters describing tone curves of the digital-image input device based at least on the linearly scaled device-independent coordinate values;
- calculating second parameters describing chromaticities of the profile based at least on the linearly scaled device-independent coordinate values;
- selectively adjusting the linearly scaled device-independent coordinate values or a derivative thereof using a piecewise linear correction function;
- generating the profile for the digital-image input device based at least on the selectively-adjusted-linearly-scaled-device-independent coordinate values, the first parameters, and the second parameters, wherein the profile is generated independently from of a relative exposure of the color chart with respect to other portions of the image outside of the color chart;
- and
- storing the profile in a computer-accessible memory.
A computer-accessible memory comprising instructions that cause a programmable processor to:
- receive a captured image of a color chart with a digital-image input device, wherein the color chart comprises a plurality of color patches;
- determine device-dependent coordinate values for each of the plurality of color patches of the captured image;
- estimate an illumination of a brightest gray patch of the plurality of color patches based at least on the device-dependent coordinate values;
- linearly scale device-independent coordinate values for each of the plurality of color patches based at least on the estimated illumination;
- and
- generate a profile for the digital-image input device based at least on the linearly scaled device-independent coordinate values.
Dependencies are inferred from the claim text.