Image dithering method enabling conversion of a gray level pixel image into a binary pixel image
US5638187A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Feb 23, 1996 |
| Grant date | Jun 10, 1997 |
| Priority date | — |
| Expiry date | Feb 23, 2016 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N1/4055
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A method converts a multi-pixel gray level raster image to a multi-pixel binary raster image, with the gray level raster image including up to P gray level values. The method first arranges the P gray level values into an ordered list. A plurality of dither matrices are then derived, each including M threshold values, each value therein being a threshold value which, when compared to a gray level pixel value enables assignment of a binary value to the pixel. In general, M and P are different integer values. If M is greater than P, the method inserts the P ordered gray level value list into one dither matrix and then inserts into the same one dither matrix at least a further portion of the ordered list, commencing with the first gray level value of the ordered list, until there is no further room for any further insertions in the one dither matrix. Then, the method inserts into a next dither matrix the portion of the ordered list not inserted into the one dither matrix and continues insertion of the ordered list until there is no further room for any further insertions. The method repeats the previous steps until the plurality of dither matrices have been derived. If M is less than …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.