Method and circuit for adjusting the size of a video frame
US5253059A · kind A · utility
Assignees
Inventors
Key dates
| Filing date | May 15, 1992 |
| Grant date | Oct 12, 1993 |
| Priority date | — |
| Expiry date | May 15, 2012 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N19/146
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
In accordance with the present invention, the number of bits used to code a frame of video is controlled by controlling the frame size. In a preprocessing stage (40) of a video coding circuit (10), each frame of video is processed by a low pass anti-aliasing filter (43,44) in the horizontal and vertical directions. The cutoff frequencies in the horizontal and vertical directions are determined by a desired frame reduction factor in the corresponding direction. Then to reduce the sampling rate in each dimension, each frame of video is processed horizontally and vertically by a shift varying filter (45,46). When the sampling rate in both the horizontal and vertical directions is reduced by M/N, the number of code bits decreases linearly with M/N.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.