Intra-frame quantizer selection for video compression
US6256423A · kind A · utility
Assignees
Inventors
Key dates
| Filing date | Dec 15, 1998 |
| Grant date | Jul 3, 2001 |
| Priority date | — |
| Expiry date | Dec 15, 2018 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N19/60
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An image is divided into one or more (e.g., foreground) regions of interest with transition regions defined between each region of interest and the relatively least-important (e.g., background) region. Each region is encoded using a single selected quantization level, where quantizer values can differ between different regions. In general, in order to optimize video quality while still meeting target bit allocations, the quantizer assigned to a region of interest is preferably lower than the quantizer assigned to the corresponding transition region, which is itself preferably lower than the quantizer assigned to the background region. The present invention can be implemented iteratively to adjust the quantizer values as needed to meet the frame's specified bit target. The present invention can also be implemented using a non-iterative scheme that can be more easily implemented in real time. The present invention enables a video compression algorithm to meet a frame-level bit target, while ensuring spatial and temporal smoothness in frame quality, thus resulting in improved visual perception during playback.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.