Apparatus and method for color space conversion in video images

Abstract

Color space conversion from a first image definition scheme to a second image definition scheme is realized by utilizing only one step of matrix multiplication and by determining whether determined RGB values are in a valid RGB region and, if not, generating a first modification factor to bring the RGB vector onto or in close proximity to the boundary of the valid RGB region. Then, the first modification factor is employed to modify in a prescribed manner the converted chroma values. In a specific embodiment of the invention, only a single matrix multiplication is employed and the otherwise additional required multiplication and/or division steps are realized by additions and/or subtractions and by employing a prescribed iterative process to bring the RGB values into or close to the valid RGB color space region. The converted chroma values are also modified by associated second modification factors also generated in the iteration process. In another specific embodiment of the invention, the converted chroma values are modified or not during an iteration depending upon whether a factor corresponding to and related to R , G , B is within a specific color space region or not. If R , G , B are within the specific color space region, the chroma values are modified by the associated second modification factors, the second modification factors are adjusted and the process is iterated. If R , G , B are other than within the specific color space region, the chroma values are not modified, the second modification factors are adjusted and the process is iterated. A prescribed number of iterations are used.