Claims
- 1. A method for modifying a screened image for repeated reproduction along a circumferential direction, the screening using a tiled supercell, the method comprising:
determining the period of the supercell in the circumferential direction; and reducing the size of the image in the circumferential direction to an integral number of supercell periods.
- 2. A method as recited in claim 1, further comprising:
enlarging the reduced image in the circumferential direction to restore the original image size.
- 3. A method as recited in claim 1, wherein the image is for output on a drum scanner on a sleeve or roller, the method further comprising:
modifying the sleeve or roller to have a circumference that matches the reduced image in the circumferential direction.
- 4. A method as recited in claim 1, further comprising:
determining the period of the supercell in the axial direction; and reducing the size of the image in the axial direction to an integral number of supercell periods.
- 5. A method as recited in claim 4, further comprising:
enlarging the reduced image in the circumferential direction to restore the original image size in the circumferential direction; and enlarging the reduced image in the axial direction to restore the original image size in the axial direction.
- 6. A method for modifying a screened image for repeated reproduction along a circumferential direction, the method comprising:
analyzing the image in a neighborhood of the seam between upper and lower edge of the image to determine any screening mismatch between the upper and lower edge of the image, upper to lower being defined in the circumferential direction; and modifying the position of halftone dots in the neighborhood to eliminate the screening mismatch at the seam.
- 7. A method as recited in claim 6,
wherein the neighborhood consists of a top part and a bottom part, wherein the analyzing includes:
searching for an area that exists in both the top and bottom parts area and wherein there is a well-defined halftone screen; carrying out screen estimation in the area that exists in both the top and bottom parts; determining the displacement that would cause the screens to line up at the seam, and wherein the position modifying includes:
displacing the pixels of the neighborhood such that the total relative displacement at the seam is the determined displacement, and such that there is no displacement at the borders of the neighborhood parts away from the seam.
- 8. A method as recited in claim 7, wherein the pixel displacement occurs in both the top and the bottom parts, and wherein the pixels are displaced in inverse proportion to the circumferential distance from the seam.
- 9. A method as recited in claim 7, wherein the displacement determining uses correlation.
- 10. A method as recited in claim 6, wherein the neighborhood consists of a top part and a bottom part, and wherein the analyzing includes:
determining the centers of the halftone dots and the screen angle of the screen in each of the areas of the neighborhood; and forming a line joining halftone dots at the screen angle in each of the top area and a bottom area of the neighborhood.
- 11. A method as recited in claim 10, wherein the halftone dot position modifying is such that the dots are displaced in inverse proportion to the circumferential distance from the seam in one area of the neighborhood while the positions of the halftone dots in the other area remain fixed.
- 12. A method as recited in claim 10, wherein the halftone dot position modifying moves the halftone dots such that the line joining the halftone dots retains smoothness.
- 13. A method as recited in claim 6, further comprising:
repairing each partial halftone dot that is originally located at the edge of the image that becomes whole after displacement.
- 14. A method as recited in claim 13, wherein the repairing of a halftone dot includes determining the average gray level in a region surrounding the halftone dot and adding pixels to the halftone dot to increase its area such that the halftone dot size matches the average gray level of the region.
- 15. A method as recited in claim 10, wherein the halftone dot position modifying displaces dots in one area while the halftone dots in the other area remain fixed.
- 16. A method as recited in claim 6, wherein the neighborhood is small compared to the total size of the image in the circumferential direction.
- 17. A method as recited in claim 6, wherein the neighborhood is a significant part of the image.
- 18. A method as recited in claim 6, wherein the neighborhood is substantially equal to the total image, such that the halftone dot position modifies the screen angle of the screen.
- 19. An apparatus to modify a screened image for repeated reproduction along a circumferential direction, the screening using a tiled supercell, the apparatus comprising:
means for accepting the image data; means to determine the period of the supercell in the circumferential direction; means to reduce the size of the image in the circumferential direction to an integral number of supercell periods; and means to output the reduced image data.
- 20. An apparatus as recited in claim 19, further comprising:
means to enlarge the reduced image in the circumferential direction to restore the original image size.
- 21. An apparatus to modify a screened image for repeated reproduction along a circumferential direction, the screening using a tiled supercell, the apparatus comprising a processing system including a processor programmed to determine the period of the supercell in the circumferential direction and to reduce the size of the image in the circumferential direction to an integral number of supercell periods.
- 22. An apparatus as recited in claim 21, wherein the processor is further programmed to enlarge the reduced image in the circumferential direction to restore the original image size.
- 23. An apparatus to modify a screened image for repeated reproduction along a circumferential direction, the apparatus comprising:
means for analyzing the image in a neighborhood of the seam between upper and lower edge of the image to determine any screening mismatch between the upper and lower edge of the image; and means for modifying the position of halftone dots in the neighborhood to eliminate the screening mismatch at the seam.
- 24. An apparatus to modify a screened image for repeated reproduction along a circumferential direction, the apparatus comprising a processing system including a processor programmed to analyze the image in a neighborhood of the seam between upper and lower edge of the image to determine any screening mismatch between the upper and lower edge of the image, and to modify the position of halftone dots in the neighborhood to eliminate the screening mismatch at the seam.
- 25. A carrier medium carrying one or more computer readable code segments that cause one or more processors of a processing system to carry out a method for modifying a screened image for repeated reproduction along a circumferential direction, the screening using a tiled supercell, the carrier medium comprising:
one or more computer readable code segments that cause one or more processors of the processing system to determine the period of the supercell in the circumferential direction; and one or more computer readable code segments that cause one or more processors of the processing system to reduce the size of the image in the circumferential direction to an integral number of supercell periods.
- 26. A carrier medium as recited in claim 25, further comprising:
one or more computer readable code segments that cause one or more processors of the processing system to enlarge the reduced image in the circumferential direction to restore the original image size.
- 27. A carrier medium carrying one or more computer readable code segments that cause one or more processors of a processing system to carry out a method for modifying a screened image for repeated reproduction along a circumferential direction, the carrier medium comprising:
one or more computer readable code segments that cause one or more processors of the processing system to analyze the image in a neighborhood of the seam between upper and lower edge of the image to determine any screening mismatch between the upper and lower edge of the image; and one or more computer readable code segments that cause one or more processors of the processing system to modifying the position of halftone dots in the neighborhood to eliminate the screening mismatch at the seam.
RELATED U.S. APPLICATION
[0001] The present invention is a continuation-in-part of U.S. patent application Ser. No. 09/801,063 to Klein, et al. titled METHOD AND APPARATUS FOR SEAMLESS IMAGING OF SLEEVES AS USED IN FLEXOGRAPHY, filed Mar. 7, 2001. U.S. patent application Ser. No. 09/801,063 is hereby incorporated herein by reference.
[0002] The present invention claims benefit of U.S. Provisional Patent Application 60/383,479 filed May 24, 2002 and titled METHOD AND APPARATUS FOR ELIMINATING SEAMS IN SCREENED IMAGE DATA FOR REPETITIVE PRINTING. of U.S. Provisional Patent Application 60/383,479 is also hereby incorporated herein by reference.
Provisional Applications (1)
|
Number |
Date |
Country |
|
60383479 |
May 2002 |
US |
Continuation in Parts (1)
|
Number |
Date |
Country |
Parent |
09801063 |
Mar 2001 |
US |
Child |
10442682 |
May 2003 |
US |