Apparatus and method for dynamic step quantization
US5101452A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 17, 1990 |
| Grant date | Mar 31, 1992 |
| Priority date | — |
| Expiry date | Dec 17, 2010 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N1/40
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
The apparatus and method of the present invention operates upon the problem of contouring that is encountered in the digital image processing field. The preferred apparatus embodiment of the invention forms quantizing steps that vary in size during the processing of signals in order to minimize contouring effects. The embodiment includes a transforming function block for receiving digital input signals each representing a magnitude value requiring quantization, the transforming function block provides an output gain value that is a function of the magnitude of the value of each received digital input signal. A quantizer is provided for receiving the digital input signals and for performing quantizing steps on the digital input signals to provide a multibit quantized digital signal. A first randomizer is used to randomize the least significant bits of the multibit quantized digital signal when the output gain value is less than or equal to threshold value. Lastly there is provided a second randomizing means for randomizing a number of bits of the multibit quantized digital signal when the output gain value from the transforming function block is greater than the threshold value.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.