Video bandwidth reduction system using a two-dimensional transformation, and an adaptive filter with error correction
US4189748A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Aug 23, 1977 |
| Grant date | Feb 19, 1980 |
| Priority date | — |
| Expiry date | Aug 23, 1997 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N19/65
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A reduction in bandwidth of two-dimensional video data is obtained by the two-dimensional transformation of the video data by means of one of a class of fast transformations followed by the elimination of certain non-significant transform coefficients prior to the transmission of the transform data. The lower-order transform coefficients or "zonal coefficients" which are usually significant in size, are always transmitted. Prior to transmission, parity bits are added to the zonal coefficients to allow error detection. An adaptive filter eliminates from the higher-order transform coefficients, those non-significant transform coefficients of magnitude less than a threshold level, which level is adjusted in response to the amount of data in the buffer memory awaiting transmission so as to transmit the most significant transform coefficients from a succession of two-dimensional data vectors. At the receiving end of the communication link the array of transform coefficients is reconstituted from the received data. The non-zonal coefficients, eliminated prior to transmission, are replaced by zeros in the reconstituted array. Transmission errors occurring in the zonal coefficients, are de…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.