Selective flattening of page description files to support color correction
View Patent ↗An imaging technique permits selective flattening of objects within page description files. The selective aspect of the flattening may pertain to the selection of particular objects to be flattened, selection of the degree of flattening to be applied to objects, or both. In some embodiments, selective flattening of objects in a page description file may be permitted based on an assessment of color correction efficacy. For example, the degree of flattening may be iteratively adjusted to achieve acceptable color correction results. Alternatively a user may be notified in the event acceptable color correction results have not been achieved. A color error between bitmap files generated from a color corrected, unflattened page description file and from a color corrected, flattened page description file may be measured. When the measured error between the two bitmaps exceeds a predetermined value, an amount of file flattening may be adjusted to reduce the measured error.
1. A method comprising:
flattening a page description file with a first degree of flattening to produce a flattened version of the page description file;
color correcting the flattened version of the page description file;
raster image processing (RIPing) the color corrected, flattened version of the page description file to produce a first bitmap;
raster image processing (RIPing) an unflattened version of the page description file to produce a second bitmap;
color correcting the second bitmap produced from the raster input processed, unflattened version of the page description file; and
determining a color error between the first and second bitmaps.
2. The method of claim 1 , further comprising flattening the page description file with a second degree of flattening when the color error exceeds a threshold value, wherein the second degree of flattening is greater than the first degree of flattening.
3. The method of claim 1 , further comprising approving the first bitmap for rendering when the color error is less than a threshold value.
4. The method of claim 1 , further comprising notifying a user of the color error when the color error exceeds a threshold value.
5. The method of claim 1 , wherein flattening includes converting at least some objects in the page description file with implicit color definitions to objects with explicit color definitions.
6. The method of claim 1 , wherein the color error comprises an average difference and a maximum difference between color values for pixels in the first and second bitmaps.
7. The method of claim 1 , wherein the page description file comprises a Portable Document Format (PDF) file or a Postscript (PS) file.
8. The method of claim 1 , further comprising iteratively flattening the page description file with increasing degrees of flattening until the color error is less than a threshold value.
9. The method of claim 1 , further comprising flattening the page description file with a degree of flattening using raster and vector settings in a document editing application.
10. The method of claim 1 , wherein color correcting the flattened version of the page description file includes converting color values within the flattened version of the page description file using a source profile and a destination profile.
11. A system comprising
a memory that stores page description files;
a processor that receives one of the page description files from the memory, the processor including:
a flattening module that flattens the page description file with a first degree of flattening to produce a flattened version of the page description file,
a color correction module that color corrects the flattened version of the page description file, and
a comparison module;
a raster image processor (RIP) that raster image processes the color corrected, flattened version of the page description file to produce a first bitmap and raster image processes an unflattened version of the page description file to produce a second bitmap,
wherein the color correction module of the processor color corrects the second bitmap produced from the raster input processed, unflattened version of the page description file and the comparison module determines a color error between the first and second bitmaps.
12. The system of claim 11 , wherein the flattening module flattens the page description file with a second degree of flattening when the color error exceeds a threshold value, wherein the second degree of flattening is greater than the first degree of flattening.
13. The system of claim 11 , wherein the processor approves the first bitmap for rendering when the color error is less than a threshold value.
14. The system of claim 11 , wherein the processor notifies a user of the color error when the color error exceeds a threshold value.
15. The system of claim 11 , wherein the flattening module converts at least some objects in the page description file with implicit color definitions to objects with explicit color definitions.
16. The system of claim 11 , wherein the color error comprises an average difference and a maximum difference between color values for pixels in the first and second bitmaps.
17. The system of claim 11 , further comprising an input device, wherein the input device comprises one of a keyboard, a mouse, a trackball, or a speech recognition device.
18. The system of claim 11 , further comprising an output device that includes the raster image processor, wherein the output device comprises one of a hard copy printer or a display monitor.
19. The system of claim 11 , further comprising an output device that includes the raster image processor, wherein the raster image processor comprises a stand-alone raster image processor.
20. The system of claim 11 , wherein the page description file comprises a Portable Document Format (PDF) file or a Postscript (PS) file.
21. The system of claim 11 , wherein the flattening module iteratively flattens the page description file with increasing degrees of flattening until the color error is less than a threshold value.
22. The system of claim 11 , wherein the flattening module flattens the page description file with a degree of flattening using raster and vector settings in a document editing application.
23. The system of claim 11 , wherein the color correction module converts color values within the flattened version of the page description file using a source profile and a destination profile.
24. A computer-readable medium comprising instructions for causing a programmable processor to:
flatten a page description file with a first degree of flattening to produce a flattened version of the page description file;
color correct the flattened version of the page description file;
raster image process (RIP) the color corrected, flattened version of the page description file to produce a first bitmap;
raster image process (RIP) an unflattened version of the page description file to produce a second bitmap;
color correct the second bitmap produced from the raster input processed, unflattened version of the page description file; and
determine a color error between the first and second bitmaps.
25. The computer-readable medium of claim 24 , further comprising instructions for causing a programmable processor to flatten the page description file with a second degree of flattening when the color error exceeds a threshold value, wherein the second degree of flattening is greater than the first degree of flattening.