Sharpening filter for images with automatic adaptation to image type
US5822467A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 27, 1996 |
| Grant date | Oct 13, 1998 |
| Priority date | — |
| Expiry date | Dec 27, 2016 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N1/4092
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A method of filtering images with a filter that is dependent on image type. For binary images, a fixed Laplacian filter is used for all pixels. For non-binary images, an automatic level-sensitive Laplacian filter is used. For non-binary images, Laplacian filter coefficients and normalization divisors are made a function of intensity on a pixel by pixel basis. Pixels indicating a high intensity may be greatly changed by neighboring pixels. Pixels indicating a low intensity receive relatively little or no filtering. In a specific example embodiment, the intensity range is divided to bands, with a different filter for each band. The resulting images are visually sharpened (edge enhanced) with very little impact in darker areas of the image.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.