Hybrid error diffusion pattern shifting reduction using programmable threshold perturbation
US5809177A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 6, 1996 |
| Grant date | Sep 15, 1998 |
| Priority date | — |
| Expiry date | Jun 6, 2016 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N1/4053
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A process eliminates pattern shifting artifacts in a printed image rendered using a hybrid high addressable error diffusion process by perturbing a threshold/image signal value relationship when a multi-level grey level is binarized. The process utilizes a programmable multi-level grey signal modifying circuit for modifying the multi-level grey signal by a predetermined value according to its grey level. The modified multi-level grey signal is binarized to a binary pixel signal according to a relationship between the modified multi-level grey signal and a threshold value. The process further generates an error corresponding to the relationship and diffuses the error to neighboring pixels. The multi-level grey signal is modified with either random noise multiplied by a grey level dependent coefficient or by a predetermined value from a checkerboard or vertical line pattern. The value from the pattern is dependent upon the grey level and pixel location of the image data.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.