DCT video signal compression device with intrafield/interfield switching and adjustable high frequency filter
US5005076A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 6, 1993 |
| Grant date | Apr 2, 1991 |
| Priority date | — |
| Expiry date | Mar 6, 2013 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N19/50
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
The digital signal is decomposed in intrafield blocks each comprising a set number of adjacent image elements, and each intrafield block, or an intrafield block or an interframe block derived therein, is subjected to a Discrete Cosine Transform and the transformed signal is applied to quantizer to generate a quantized signal which is encoded at variable length and loaded to a transmission buffer, the quantization resolution being inversely proportional to the buffer fill rate. According to the invention, a digital low-pass filter is connected to filter the block to be subjected to Discrete Cosine Transform, and is subjected to the buffer so that its upper-frequency cutoff lowers as the buffer fill rate increases.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.