Halftone-independent scanner profiling
View Patent ↗A method and system is disclosed for characterizing a color scanner comprising generating a halftone-independent target of color patches, printing the target on a color hardcopy device, measuring the target to obtain device-independent color values, scanning the target to obtain scanner color values, and building a scanner profile that relates scanned color values to device-independent color values.
1. A halftone-independent method for characterizing a color scanner operatively associated with a printer:
printing a target set of basic patches on the printer, the target set of basic patches including binary patterns that characterize dot overlaps associated with all possible halftone patterns associated with the printer, wherein the basic patches are generated with dot patterns derived from the binary patterns and the dot patterns represent various dot patterns included in the plurality of halftone patterns associated with the printer;
measuring the target set of basic patches to obtain device-independent color values;
scanning the target set of basic patches with the color scanner and obtaining scanner color values; and,
relating the scanner color values to the device-independent color values for generating a scanner profile characterizing the color scanner.
2. The method of claim 1 wherein printing the target set comprises printing binary 2×2 spatial dot arrangements.
3. The method of claim 1 wherein relating includes generating a multidimensional lookup table corresponding measured device-independent color values to scanner color values.
4. The method of claim 1 wherein the device-independent color values are CIELAB values, and scanner values are RGB values.
5. The method of claim 2 further including generating the target set as a target of less than 1,072 patches based on a 2×2 binary printer model.
6. The method of claim 1 wherein the target set is printed with cyan, magenta, yellow and black colorants.
7. A system for building a color profile for a scanner
operatively associated with a printer, including:
a halftone-independent scanner profiling target set comprising a plurality of patches, the target set including binary patterns that form a basis set for a plurality of halftone methods associated with the printer, the binary patterns characterizing dot overlaps associated with all possible halftone patterns associated with the printer;
at least one print of the profiling target set generated on the printer;
a plurality of device-independent color values measured from the at least one print;
a corresponding plurality of scanner color value generated by the scanner from the at least one print; and,
a relational database relating the plurality of measured device-independent color values to corresponding ones of the plurality of scanner color values.
8. The system of claim 7 wherein the target set comprises binary 2×2 spatial dot arrangements.
9. The system of claim 8 wherein the target set is less than 1,072 color patches based on a 2×2 binary printer model.
10. The system of claim 7 wherein the relational data base comprises a multidimensional lookup table.
11. The system of claim 7 wherein the device-independent color values are CIELAB values, and scanner values are RGB values.
12. The system of claim 7 wherein the target set is printed with cyan, magenta, yellow and black colorants.
13. A method for characterizing an image capture device for capturing a printed image comprising:
printing a target set of patches on a printer associated with the image capture device, the target set including binary patterns that form a basis set for a plurality of halftone methods associated with the printer and, the patches are generated with dot patterns that are independent of the halftone method, the binary patterns characterizing dot overlaps associated with all possible halftone patterns associated with the printer;
measuring the printed target set to obtain device-independent color values;
capturing the printed target set with the image capture device to obtain device-dependent color values; and,
relating the device-independent color values to the device-dependent color values for generating a profile characterizing the image capture device.
14. The method of claim 13 wherein printing and measuring are performed a priori in an offline step.
15. The method of claim 13 wherein printing the target set comprises printing binary 2×2 spatial dot arrangements.
16. The method of claim 13 wherein relating includes generating a multidimensional lookup table corresponding measured device-independent color values to captured device-dependent color values.