Image processing method and apparatus
US6510252B1 · kind B1 · utility
Assignee
Inventor
Key dates
| Filing date | Feb 23, 1999 |
| Grant date | Jan 21, 2003 |
| Priority date | — |
| Expiry date | Feb 23, 2019 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N1/4052
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An image processing method and an image processing apparatus are provided to maintain image quality through simple processing while reducing the number of gradation levels of image data by error diffusion process. In an image processing apparatus, data outputted from a filter is subtracted from input image data x(i, j) at the subtracter. Data outputted from the subtracter is quantized at a quantizer. Data outputted from the quantizer is outputted as output image data y(i, j). Furthermore, the data outputted from the subtracter is subtracted from the data outputted from the quantizer at a second subtracter to produce quantization error e(i, j). At a filter section, filtering process is performed on the quantization error e(i, j). Data outputted from the filter section is inputted to the first subtracter. According to the gradation values of the input image data x(i, j), weight coefficient selecting section selects a filter coefficient, which corresponds to weight coefficient for error diffusion at the filter section, and sets it up in the filter section.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.