Secondary color corrector
US5412433A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 2, 1993 |
| Grant date | May 2, 1995 |
| Priority date | — |
| Expiry date | Aug 2, 2013 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N23/86
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An improved method and apparatus for color correction normalizes two of the three color signals as a function of the third. In the preferred embodiment, an image comprising red, green and blue (RGB) signals are converted to a luminance Y signal, a saturation signal and a hue signal. The luminance and saturation signals are normalized as a function of hue. In the most preferred embodiment, for all fully saturated colors, the luminance values are normalized to a value of 0.5, and the saturation values to unity for all values of hue. The normalized values of saturation and luminance are utilized with the hue value in a secondary color corrector. The color corrected values of saturation and luminance are denormalized as a function of color corrected hue. Optionally, the color corrected luminance, saturation and hue may be converted to RGB signals for output. In one aspect of this invention, the normalized luminance signal is not used for relatively small values of saturation. In another aspect of this invention, multiple color correction regions are provided on an image. Overlapping regions are assigned priorities.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.