Controlling an electrophotographic printer using an image region database
View Patent ↗A method for controlling an electrophotographic printing system to print digital image data for an image region. An image region database stores data characterizing a plurality of reference image regions, each reference image region having one or more associated system control parameters that are appropriate for use in printing the reference image region. The system control parameters can include parameters related to correcting color registration errors. The image region to be printed is compared with the reference image regions in the image region database, and a similar reference image region is selected. The image region is printed using the system control parameters associated with the selected similar reference image region.
1. A method for controlling a digital printing system, comprising:
receiving digital image data for an image region to be printed by the digital printing system;
designating an image region database stored in a processor-accessible memory including data characterizing a plurality of reference image regions, each reference image region having one or more associated system control parameters that are appropriate for use in printing the reference image region on the digital printing system;
using a data processing system to compare the image region to be printed with the reference image regions in the image region database and select a reference image region that is sufficiently similar to the image region to be printed; and
using the digital printing system to print the received digital image data for the image region by applying one or more colorants onto a print medium, wherein the digital printing system includes an electrophotographic printing module that is controlled using the system control parameters associated with the selected similar reference image region during the printing of at least a subset of the image region.
2. The method of claim 1 wherein the data characterizing a reference image region includes a parametric representation of the reference image region.
3. The method of claim 2 wherein the determination of the parametric representation includes:
determining an ink coverage profile representing a distribution of ink within the reference image region; and
representing the ink coverage profile using a series expansion based on a set of orthogonal basis functions;
wherein coefficients determined for a plurality of the basis functions are designated to be parameters for the parametric representation.
4. The method of claim 1 wherein the data characterizing a reference image region includes digital image data for the reference image region, the digital image data including pixel values for an array of image pixels.
5. The method of claim 4 wherein the comparison of the image region to be printed with a particular reference image region includes computing a difference image representing a difference between digital image data for the image region to be printed and the digital image data for the particular reference image region.
6. The method of claim 5 further including determining a difference metric by performing a statistical analysis on the difference image.
7. The method of claim 5 wherein the difference image has a lower spatial resolution than the image region to be printed.
8. The method of claim 7 wherein the reference image regions in the image region database are stored at the lower spatial resolution, and wherein the digital image data for the image region to be printed is down-sample to the lower spatial resolution before the difference image is computed.
9. The method of claim 1 wherein difference parameters are determined representing differences between the reference image regions and the image region to be printed.
10. The method of claim 9 wherein the reference image region having the smallest corresponding difference parameter is designated to be the selected similar reference image region.
11. The method of claim 9 wherein the selected reference image region is designated to be sufficiently similar to the image region to be printed if the difference parameter is smaller than a predefined difference threshold.
12. The method of claim 1 wherein one or more system configuration parameters are associated with the reference image regions in the image region database, and wherein the selection of the similar reference image region includes comparing the system configuration parameters associated with the reference image regions to system configuration parameters to be used when the received digital image data for the image region is printed.
13. The method of claim 1 wherein the reference image regions in the image region database are selected to be representative of different types of image regions that are commonly printed.
14. The method of claim 1 wherein the image region to be printed is added to the image region database as a new reference digital image.
15. The method of claim 14 wherein the image region to be printed is added to the image region database if it is determined to be sufficiently different from all of the reference image regions in the image region database.
16. The method of claim 1 wherein the digital printing system is a color printing system that prints images having a plurality of color channels, and wherein the system control parameters include one or more color registration parameters that are used to control the registration between two or more different color channels.
17. The method of claim 16 wherein the color registration parameters include an in-track shift value, a cross-track shift value, an in-track magnification factor, a cross-track magnification factor, or an image rotation value.
18. The method of claim 1 wherein the digital printing system is a color printing system that prints images having a plurality of color channels, and wherein the system control parameters include a color adjustment parameter that is used to adjust color reproduction characteristics.
19. The method of claim 1 wherein the digital printing system has a plurality of different print modes, and wherein the system control parameters include a print mode selection parameter that is used to select between the different print modes.
20. The method of claim 1 wherein the digital printing system includes a media de-curling subsystem for reducing curl in the print medium, and wherein the system control parameters include a de-curling subsystem control parameter that is used to control a setting on the de-curling subsystem.
21. The method of claim 1 wherein the electrophotographic printing module includes an electrophotographic print engine, and wherein the system control parameters include one or more electrophotographic print engine control parameters that are used to control a setting on the electrophotographic print engine.
22. The method of claim 1 wherein the processor-accessible memory used to store the image region database and the data processing system used to compare the image region to be printed with the reference image regions in the image region database are at a different location than the digital printing system.
23. The method of claim 1 wherein the processor-accessible memory used to store the image region database and the data processing system used to compare the image region to be printed with the reference image regions in the image region database are components of the digital printing system.
24. The method of claim 1 wherein the digital printing system prints on individual sheets of print medium, and wherein the image region to be printed corresponds to a single sheet of print medium.
25. The method of claim 1 wherein the digital printing system prints on a continuous web of print medium.