Transform processing method for reducing noise in an image
US4553165A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Aug 11, 1983 |
| Grant date | Nov 12, 1985 |
| Priority date | — |
| Expiry date | Aug 11, 2003 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06T5/70
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
An improved image processing method reduces noise in a sampled image while minimizing unintended distortion of image features. Image signals are generated representative of the light value of elements of the image. These signals are formed into signal arrays aligned to blocks of image elements. The signal arrays are transformed by a set of 4 by 4 Walsh-Hadamard functions into a corresponding set of coefficient signals. Certain of these coefficient signals represent the difference between the light value of each image element and an average light value over an image region smaller than the block being transformed. By modifying--i.e., coring or clipping--and inverting only these selected coefficient signals, artifacts related to the introduction of "false" edge-like structure are reduced in the reconstructed image. In addition, in a multi-stage processing method, the excluded coefficient signals may represent the input signals to the next stage.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.