Image processing apparatus and method that adds correction signal to average density and digitizes accordingly
US5610999A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 28, 1994 |
| Grant date | Mar 11, 1997 |
| Priority date | — |
| Expiry date | Jun 28, 2014 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N1/403
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
There is disclosed a method for converting multi-level image data into binary image data and an apparatus therefor. An average density is calculated from the already binarized density of pixels positioned in a predetermined area around an object pixel, and the threshold value for binarization is set by adding a fixed bias value and varying dither signals to the average density, and the error generated in the binarization is distributed to the unbinarized pixels positioned behind. The addition of the fixed bias prevents formation of a spot-free white area in the vicinity of an edge or in the initial stage of processing, and the addition of dither signals prevents texture formation in the low density area.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.