| 摘要 |
During post-processing of video data in a YUV color space it may be necessary, for instance for immersive video conferences, to separate a video object in the image foreground from the known image background. Hitherto, rapid, locally limited deviations in illumination in the actual image to be examined, in particular shadows and brightenings, could not be compensated. The inventive recognition and compensation method, however, can compensate in real time shadows and brightenings, even at great quantities of image data by directly utilizing different properties of the technically based YUV color space. Chrominance, color saturation and color intensity of an actual pixel (P1) are approximated directly from associated YUV values (alpha, a, b) which leads to the avoidance of time-consuming calculations. The recognition of rapid deviations in illumination carried out in the YUV color space is based upon the approximation of a chrominance difference by an angle difference (alpha1-alpha2) of the pixels (P1, P2) to be compared, preferably in a plane (U, V) of the YUV color space. This proceeds on the assumption that the chrominance of a pixel at the occurrence of shadows and brightenings remains constant in spite of varying color saturation and color intensity. The method in accordance with the invention may be supplemented by a rapid decision program including additional decision parameters which excludes complex calculations of angle operations and separation error, even at significant deviations in illumination. |
