Color gradation correction method and apparatus
US5296920A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 16, 1992 |
| Grant date | Mar 22, 1994 |
| Priority date | — |
| Expiry date | Sep 16, 2012 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N23/83
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A gradation correction apparatus for processing R, G, and B input signals includes a luminance signal conversion device for obtaining the original luminance signal, which is before gamma conversion, from the input signals, a luminance gamma conversion device for gamma converting the original luminance signal to the desired gradation characteristics to obtain a gamma converted luminance signal, a correction coefficient calculation means for obtaining a ratio of the gamma converted luminance signal to the original luminance signal, a first RGB operation means for multiplying the ratio by each of the R, G, and B input signals for obtaining primary gradation-corrected R, G, and B signals; a color difference signal operation means for producing a difference between each of the R, G, and B input signals and the original luminance signal; a second RGB operation means for adding the gamma converted luminance signal to each of the difference for obtaining secondary gradation-corrected R, G, and B signals; and an RGB determination means for obtaining final gradation-corrected R, G, B signals based on the primary and secondary gradation-corrected R, G, and B signals.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.