Method and filter for reducing the blocking effect in image transmission and storage
US5982442A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Nov 28, 1997 |
| Grant date | Nov 9, 1999 |
| Priority date | — |
| Expiry date | Nov 28, 2017 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N19/86
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
For image transmission, image data is compressed block by block, and the compressed data is transmitted and decompressed. Due to an information loss during transmission, discontinuities are visible in pictures thus restored, particularly at block boundaries ("blocking effect"). The higher the bit rate, the more visible the discontinuities will be. This is improved by refining the prior art filter. Information for reducing the error is derived from the boundaries of the block, and the filter size is enlarged to 2.times.n+1 pixels, with n=2, 3, 4 preferably limited to one half the number of pixels on one side making up the block. Besides the signal and noise activity of a block, the filter determines both the pixels inside the block and the pixels outside the block. The determination is made by means of the one-dimensional filter in the horizontal and vertical directions.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.