Loop filter and loop filtering method
US5974197A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 14, 1997 |
| Grant date | Oct 26, 1999 |
| Priority date | — |
| Expiry date | Jul 14, 2017 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N19/86
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A loop filtering method and a loop filter therefor are provided. The loop filtering method includes the steps of: (a) generating a binary edge map by comparing a value obtained by operating each pixel of the image data using a predetermined one-dimensional gradient operator with a predetermined threshold value; (b) applying a filter window with a predetermined size to the generated binary edge map to check whether an edge information exists within the filter window; (c) filtering the pixel value of the corresponding filter window by a pixel using predetermined first weights to generate a new pixel value if it is determined in the step (b) that the edge information does not exist; and (d) filtering the pixel value of the corresponding filter window by a pixel using predetermined second weights to generate a new pixel value if it is determined in the step (b) that the edge information exists, wherein the filtering is not performed in the step (d) if the pixel at the center of the filter window is edge information. Therefore, blocking effect and ringing noise are removed from the image passed through block-based compression restoration, improving the quality of the restored image.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.