Video signal encoding apparatus utilizing control of quantization step size for improved picture quality
US5237410A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Nov 29, 1991 |
| Grant date | Aug 17, 1993 |
| Priority date | — |
| Expiry date | Nov 29, 2011 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N19/20
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A video signal encoding apparatus of the type in which inter-frame difference values for respective picture elements are subjected to orthogonal transform processing and the resultant transform coefficients are quantized and encoded, with respective values of quantization step size applied to successive 2-dimensional blocks of picture element values being varied such as to control the encoded data bit stream to a constant bit rate, in which the quantization step size for each block is also controlled in accordance with whether or not the block lies on a border between a visually smooth region of the picture expressed by the video signal and a region in which substantial changes occur in the picture. The step size can thereby be set to be sufficiently small, in the case of specific blocks for which is necessary to use a small size of quantization step in order to prevent noise from appearing in the picture obtained from the decoded video signal.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.