Adaptive non-linear quantizer
US5136377A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 11, 1990 |
| Grant date | Aug 4, 1992 |
| Priority date | — |
| Expiry date | Dec 11, 2010 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N19/152
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A quantizer, with quantization control that is sensitive to input signal characteristics and to output buffer fullness responds to an input signal that is divided into blocks and DCT transformed. The transformed signal is analyzed to develop a brightness correction and to evaluate the texture of the image and the change in texture in the image. Based on these, and in concert with the human visual perception model, perception threshold signals are created for each subband of the transformed signal. Concurrently, scale factors for each subband of the transformed signal are computed, and a measure of variability in the transformed input signal is calculated. A measure of the fullness of the buffer to which the quantizer sends its encoded results is obtained, and that measure is combined with the calculated signal variability to develop a correction signal. The correction signal modifies the perception threshold signals to develop threshold control signals that are applied to the quantizer. The scale factors are also applied to the quantizer, as well as a global target distortion measure.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.