Color input scanner calibration system

• US 20070131855A1
• Filed: 12/13/2005
• Published: 06/14/2007
• Est. Priority Date: 12/13/2005
• Status: Active Grant

• Current Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Original Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Inventors: Banton, Martin, Hosier, Paul
• Granted Patent: US 7,271,380 B2
• Time in Patent Office: Days
• US Class Current: 250/234
• CPC Class Codes: G01J 3/51 using colour filters
• CPC Class Codes: G01J 3/513 having fixed filter-detector pairs
• CPC Class Codes: G01J 3/524 Calibration of colorimeters
• CPC Class Codes: H04N 1/486 with separate detectors, each detector being used for one specific colour component
• CPC Class Codes: H04N 1/6033 using test pattern analysis H04N1/6055 takes precedence

Abstract

A photosensitive apparatus, such as scanner, includes a plurality of pixels, each pixel having associated therewith a set of photosensors, each photosensor filtered to record a primary color. The photosensors are exposed to light of each primary color separately, thereby deriving test signals. A cross-color correction factor for the pixel is derived from the test signals. The cross-color correction factor is used in processing signals output from the pixel when an image is being recorded, so as to isolate the effects of signal crosstalk between closely-spaced photosensors of different colors.

Claims

1. A method of operating a photosensitive apparatus, the apparatus including a first photosensor sensitive to a first color and a second photosensor sensitive to a second color, comprising:

exposing the first photosensor and the second photosensor to light of substantially the first color, thereby deriving test signals from the first photosensor and the second photosensor;

exposing the first photosensor and the second photosensor to light of substantially the second color, thereby deriving test signals from the first photosensor and the second photosensor;

deriving from the test signals a cross-color correction factor;

using the cross-color correction factor in processing signals output from the first photosensor and the second photosensor when an image is being recorded.

2. The method of claim 1, wherein the first photosensor and the second photosensor are defined in a single chip.

3. The method of claim 2, wherein the first photosensor and the second photosensor are in substantial proximity on the chip.

4. The method of claim 1, wherein the first photosensor and the second photosensor are associated with a single pixel.

5. The method of claim 4, wherein there are provided a plurality of pixels in the apparatus, and the exposing is performed with each of the plurality of pixels.

6. The method of claim 4, wherein there are provided a plurality of pixels in the apparatus, and the exposing is performed with substantially all of the plurality of pixels.

7. The method of claim 1, wherein the cross-color correction factor is expressible as a matrix.

8. The method of claim 1, further comprising

providing a first test area and a second test area within the apparatus, the first test area reflecting light of substantially the first predetermined color into the first photosensor and the second photosensor, and the second test area reflecting light of substantially the second predetermined color into the first photosensor and the second photosensor.

9. The method of claim 1, the using comprising

using the cross-color correction factor in combination with a main look-up table, the main look-up table relating to a response to white light.

10. A method of operating a photosensitive apparatus, the apparatus including a plurality of pixels, each pixel having associated therewith a first photosensor sensitive to a first color, a second photosensor sensitive to a second color, and a third photosensor sensitive to a third color, comprising, for each of a plurality of pixels:

exposing the first photosensor, the second photosensor, and the third photosensor to light of substantially the first color, thereby deriving test signals from the first photosensor, the second photosensor, and the third photosensor;

exposing the first photosensor, the second photosensor, and the third photosensor to light of substantially the second color, thereby deriving test signals from the first photosensor, the second photosensor, and the third photosensor;

exposing the first photosensor, the second photosensor, and the third photosensor to light of substantially the third color, thereby deriving test signals from the first photosensor, the second photosensor, and the third photosensor;

deriving from the test signals a cross-color correction factor for the pixel; and

using the cross-color correction factor in processing signals output from the pixel when an image is being recorded.

11. The method of claim 10, the method being applied to substantially all pixels associated with the apparatus.

12. The method of claim 10, wherein at least the first photosensor and the second photosensor for a pixel are defined in a single chip.

13. The method of claim 12, wherein at least the first photosensor and the second photosensor for a pixel are in substantial proximity on the chip.

14. The method of claim 10, further comprising

providing a first test area and a second test area within the apparatus, the first test area reflecting light of substantially the first predetermined color into the first photosensor and the second photosensor, and the second test area reflecting light of substantially the second predetermined color into the first photosensor and the second photosensor.

15. The method of claim 10, the using comprising

using the cross-color correction factor in combination with a main look-up table, the main look-up table relating to a response to white light.