Memory efficient compression apparatus in an image processing system
US6621934B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Aug 12, 1997 |
| Grant date | Sep 16, 2003 |
| Priority date | — |
| Expiry date | Aug 12, 2017 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N19/593
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An image processor produces a DPCM prediction error to be quantized. If the prediction error value is positive, the value passes unchanged to a quantizer. If the prediction error value is negative, a bias value is added to the prediction error value to produce a positive number within the operating limits of the quantizer. Biased prediction error values are quantized. Because all values received by the quantizer are positive and within the current quantizer limits, the quantization table used by the quantizer need not include quantization values for negative prediction error values. This reduces the scope of prediction error values by a factor of two, doubling quantization resolution.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.