Method for trapping raster data in a run-length encoded form
US6844942B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Oct 2, 2002 |
| Grant date | Jan 18, 2005 |
| Priority date | — |
| Expiry date | Aug 14, 2023 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N1/58
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A method of correction for toner misregistration in color printing systems, specifically for run length encoded image data. This method, called “trapping”, usually involves extending the color separations one or more pixels to overlay the edge. The color of the “trap zone” is chosen such that it is nearly imperceptible in the presence of the two initial colors. Our approach assumes the existence of a “trap generator”, which provides a trap color given two input colors.In run length encoded image format, the image is comprised of an array of “scanlines”, consisting of a string of “runs” that are specified by a minimum position in the fast (horizontal) direction, a length, and a color. We describe a method of trapping involving the following steps: 1) inspecting the run lengths in each scanline to determine the color edges of the image; 2) sending the colors at the boundaries to the trap generator to determine the trap color; and 3) modifying the intersecting runs with the trap color. The result is an efficient elimination of the edge defects at color boundaries, which is enabled by the run length encoded image format.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.