Method for half tone phase matching at run boundaries
US6798920B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Mar 29, 2000 |
| Grant date | Sep 28, 2004 |
| Priority date | — |
| Expiry date | Mar 29, 2020 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N1/409
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A method for correcting a white line artifact between low and high frequency printed pixels. A printer may be able to print either a high or low frequency halftone pixels in some locations, but may be able to print only high frequency halftone pixels in other locations, the latter known as out of phase locations. If the image data is in run length encoded form, and the printer tries to print a low frequency pixel in an out of phase location, no pixel will be printed in that location and a white space results. The remedy is to test at the beginning and end of low frequency runs bordering high frequency runs. If the first (last) low frequency pixel of an original run is in an out of phase location, a one pixel run of the high frequency screen and of the low frequency color is added before (after) the original run, and the run length of the low frequency run is decreased by one pixel.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.