Halftoning device and halftoning method and laser printer including the same
US7948659B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Aug 22, 2006 |
| Grant date | May 24, 2011 |
| Priority date | — |
| Expiry date | Mar 3, 2029 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N1/4072
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A halftoning device that converts an input pixel signal of 8 bits per pixel into an output pixel signal of r bits per pixel(r<8), the halftoning device includes: a gradation correction unit that expands the input pixel signal into an expanded pixel signal of n bits per pixel(n>8); a threshold value array storage that stores a threshold value array having a threshold value of 8 bits; and a threshold value expansion unit that expands the threshold value of 8 bits to expanded threshold value of n bits per pixel. A range of the expanded pixel signal output from the gradation correction unit is matched with a range of the expanded threshold value. The output pixel signal is set according to a comparison of the expanded pixel signal with the expanded threshold value corresponding to the threshold value that is selected for each input pixel signal.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.