GPU-Based background illumination correction for blue screen matting

Separation of foreground objects from an almost constant backing color for video applications is still a common problem ([1],[2]). For non-realtime situations there is a wide variety of different powerful mathematical approaches that can deal with most of the matting problems. For SD/HD studio realtime keyers most solutions are not applicable due to their algorithm complexity or high effort in user interaction. Excellent hardware keyers, such as Ultimatte^TM work on most occasions, but even under controlled lighting in a blue-/greenscreen matting problems may occur, or creativity is limited by necessary lighting conditions. As a preprocessing algorithm for traditional chroma keying systems, we present a simple background illumination correction based approach for improving matting problems with uneven or poor lit blue-/greenscreens. Using the computational power of GPU computing (GPGPU [3]) the presented algorithm is realtime capable and offers an improvement for achievable mattes quality.