Method and apparatus for non-linear dithering of digital images
US5371515A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 28, 1989 |
| Grant date | Dec 6, 1994 |
| Priority date | — |
| Expiry date | Sep 28, 2009 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N1/4057
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
The method and apparatus of the present invention takes into consideration that the eye is more sensitive to intensity variations at low levels of intensity than at high levels of intensity and produces higher quality dithered images by employing a sectioned or piecewise linear quantization strategy which sacrifices the fineness of interval spacing at the high end of the intensity scale in order to achieve greater accuracy of reproduction at the low end. The input intensity values are divided into a plurality of sub-ranges indicative of low intensities and high intensities. The number of input intensity levels allocated to the low intensity sub-ranges is small and the number of quantized or output intensity levels allocated to the low intensity sub-ranges is large compared to those allocated to the high intensity sub-ranges such that the interval spacing at the low intensity sub-ranges is small to provide greater accuracy at the low intensity levels where the eye is most sensitive.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.