Method of measuring the noise in an active video image and device for implementing the method
US5394192A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Mar 29, 1993 |
| Grant date | Feb 28, 1995 |
| Priority date | — |
| Expiry date | Mar 29, 2013 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N5/21
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A method of measuring the noise in an active video image. During a given processing period, for each pixel of a video image considered to be stationary, the difference f.sub.d between the video signal corresponding to this pixel and the video signal corresponding t the pixel at the same spatial position in a preceding image is calculated. The square of the absolute value of the difference is calculated so as to obtain a value .vertline.f.sub.d .vertline..sup.2, and the value .vertline.f.sub.d .vertline..sup.2 is added to previously obtained values so as to form a sum value .SIGMA..vertline.f.sub.d .vertline..sup.2. The above operations are repeated until the number of pixels processed is equal to a given threshold value N.sub.0, or until the end of the processing period. At the end of the processing period, if the number of pixels processed is equal to the threshold value, the value .SIGMA..vertline.f.sub.d .vertline..sup.2 is used to determine a reference point giving a new noise-reduction coefficient k.sub.min, otherwise the former reference point is kept. The invention applies especially to television.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.