Reducing halos in spatially dependent gamut mapping
US6826304B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Mar 13, 2002 |
| Grant date | Nov 30, 2004 |
| Priority date | — |
| Expiry date | Jan 7, 2023 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N1/6058
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A method and apparatus for color image processing using gamut mapping reduces halo artifacts by correcting terms in a gamut mapping algorithm. The color image may be represented by f, the in gamut image by g, the target gamut by C, and the gamut constraint by c. The method for reducing halo artifacts includes two correction steps. First a color distance term L2 in the gamut mapping algorithm is corrected. Second, a distance measure of an image gradient in the gamut mapping algorithm is corrected. The first correcting step comprises computing a function u=projectC(ƒ). The second correcting step comprises computing a scaled down function for f. Next, a function g(x,y) is determined that minimizes a functional comprising the color distance term and the image gradient term. The solution may be determined by iteration using a gradient descent operation by first initializing g0=projectC(ƒ), and then performing one or more iteration steps to compute g(x,y).
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.