System and method for dithering and quantizing image data to optimize visual quality of a color recovered image
US5905504A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 19, 1996 |
| Grant date | May 18, 1999 |
| Priority date | — |
| Expiry date | Dec 19, 2016 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N1/648
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A color graphics pipeline has a separate encoder with a dither table for processing each color value in pixel data received from a host processor or rasterizer. The encoders modify color values and dither noise values and also combine both positive and negative dither noise values with the color values, for independent optimization of each color and for better edge detection in a color recovery filter within a decoder of the pipeline. Each encoder comprises the following elements. A comparator mechanism compares a color value with a predetermined cutoff value. A dither table provides dither noise values. An offset mechanism modifies the dither noise values to derive a modified dither noise value when the color value is greater than or equal to the predetermined cutoff value. An aliasing mechanism aliases the color value with other color values below the predetermined cutoff value to derive an aliased color value when the color value is less than the predetermined cutoff value. An adder mechanism adds the unmodified dither noise or modified dither noise to the aliased color value or nonaliased color value, respectively, to derive the dithered color value. A clamping mechanism ensure…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.