Video bandwidth reduction system employing interframe block differencing and transform domain coding
US4541012A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jan 4, 1982 |
| Grant date | Sep 10, 1985 |
| Priority date | — |
| Expiry date | Jan 4, 2002 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N19/91
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
Video type information signals are compressed for transmission and reproduction by comparing corresponding blocks of time domain information signals from successive fields, converting a block of the time domain information signals to a transform domain signal represented by discrete cosine transform coefficients when the difference between the corresponding blocks exceeds a block difference threshold, and encoding the transform domain coefficients for transmission to a decoding site. Corresponding blocks of time domain information signals from successive fields are compared by storing the successive fields in memory on a pixel by pixel basis, retrieving each block on a pixel by pixel basis, forming the difference between corresponding pixels from the successive blocks, squaring the resulting difference signal, summing the squares and dividing by the number of pixels per block. Successive fields are merged by weighted summing of corresponding pixels.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.