Bitrate damper for selecting quantization levels for image encoding
US5926569A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Sep 28, 1995 |
| Grant date | Jul 20, 1999 |
| Priority date | — |
| Expiry date | Sep 28, 2015 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N19/172
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
For each image, an initial set of quantization (Q) levels is selected based on the pixel data. The pixel data are transformed to blocks of transform coefficients. The initial set of Q levels is incremented and decremented. The incremented Q levels are used to generate a low estimate of bitrate for the transform coefficients and the decremented Q levels are used to generate a high estimate of bitrate for the transform coefficients. The low and high bitrate estimates are compared to a specified target bitrate to generate Q-level adjustments. The Q-level adjustments are used to select the Q levels to encode fully the quantized coefficients of the current image in the sequence of images.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.