Image processing method and apparatus
US6011878A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 24, 1997 |
| Grant date | Jan 4, 2000 |
| Priority date | — |
| Expiry date | Sep 24, 2017 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N1/4056
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
Disclosed are an image processing method and apparatus for applying spatial filtering processing to n-bit multilevel image data, converting the processing image data to two-level or multilevel image data and converting the resulting image data to data capable of being expressed using high-resolution dots. The filtered image data is subjected to a luminance-to-density conversion and is further converted to two or four levels by a four-level/two-level conversion circuit which makes common use of circuitry for executing both two-level error diffusion processing and four-level error diffusion processing. The four-level/two-level conversion circuit clamps the error produced in four-level conversion processing to the number of significant bits of the error produced at execution of the two-level conversion processing. As a result, a common circuit can be used for both the two-level conversion processing and the four-level conversion processing.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.