Color detection using grayscale and position information
View Patent ↗The color of a surface is determined by tracking the position of the surface using grayscale image sensing and then using captured grayscale image information, position information, and grayscale-to-color conversion information to determine color. In one embodiment, the technique requires establishing grayscale-to-color conversion information and a relationship between position and the grayscale-to-color conversion information. A calibration pattern is printed on a piece of paper and the surface of the paper is illuminated. Grayscale image information and position information related to the surface is generated in response to the illumination. Color-specific portions of the grayscale-to-color conversion information that are to be used in color determination are selected based on the position information. Grayscale image information related to the calibration pattern is then compared to the selected color-specific portions of the grayscale-to-color conversion information to determine the color of the calibration pattern.
1. A method for determining color comprising:
establishing grayscale-to-color conversion information;
establishing a relationship between position and the grayscale-to-color conversion information;
illuminating a surface;
generating grayscale image information and position information related to the surface in response to the illumination;
selecting a portion of the grayscale-to-color conversion information in response to the position information; and
comparing the grayscale image information to the selected portion of the grayscale-to-color information to generate color information related to the surface.
2. The method of claim 1 wherein the comparison includes determining a color of the surface.
3. The method of claim 1 wherein the comparison includes determining if a color of the surface matches an expected color.
4. The method of claim 1 further comprising printing a calibration pattern having color-specific features on the surface before the surface is illuminated.
5. The method of claim 4 further comprising using the color information to make a determination related to color ink that is used to print the calibration pattern.
6. The method of claim 1 wherein generating position information includes correlating frames of image information to determine the relative displacement.
7. The method of claim 1 wherein generating position information includes correlating frames of image information to determine the displacement of the surface relative to a detection system.
8. The method of claim 1 wherein selecting a portion of the grayscale-to-color conversion information includes selecting color-specific grayscale-to-color conversion information.
9. The method of claim 1 wherein selecting a portion of the grayscale-to-color conversion information includes selecting a set of grayscale-to-color conversion information that is specific to one color.
10. The method of claim 1 wherein selecting a portion of the grayscale-to-color conversion information includes selecting a set of grayscale-to-color conversion information that is specific to one of red, green, or blue.
11. A system for determining color comprising:
memory configured to store grayscale-to-color conversion information and a relationship between position and the grayscale-to-color conversion information;
a light source configured to illuminating a surface;
an image sensor configured to generate image information in response to light that reflects off of the surface;
navigation logic configured to generate position information related to the surface in response to the image information; and
color determination logic configured to select a portion of the grayscale-to-color conversion information in response to the position information and to compare the grayscale image information to the selected portion of the grayscale-to-color information to generate color information related to the surface.
12. The system of claim 11 further comprising a print system configured to print a calibration pattern having color-specific features on the surface before the surface is illuminated by the light source.
13. The system of claim 12 further comprising ink status logic configured to use the color information from the color determination logic to make a determination related to color ink that is used by the print system to print the calibration pattern.
14. The system of claim 11 wherein the navigation logic generates the position information by correlating frames of the image information to determine relative displacement of the surface.
15. The system of claim 11 wherein the navigation logic generates the position information by correlating frames of image information to determine the displacement of the surface relative to the image sensor.
16. The system of claim 11 wherein the color determination logic is configured to select grayscale-to-color conversion information that is specific to a single color in response to the position information.
17. A method for determining color comprising:
establishing grayscale-to-color conversion information;
establishing a relationship between position and the grayscale-to-color conversion information;
printing a calibration pattern having color-specific features onto a surface, the calibration pattern exhibiting the relationship between position and the grayscale-to-color conversion information;
illuminating the surface;
generating grayscale image information and position information related to the surface in response to the illumination;
selecting a color-specific set of the grayscale-to-color conversion information in response to the position information; and
comparing the grayscale image information to the selected color-specific set of the grayscale-to-color information to generate color information related to the surface.
18. The method of claim 17 wherein the comparison includes determining a color of the surface.
19. The method of claim 17 further comprising using the color information to make a determination related to color ink that is used to print the calibration pattern.
20. The method of claim 17 wherein generating position information includes correlating frames of image information to determine the relative displacement.