An object-based approach to color subsampling

We propose an object-based approach to image subsampling in the chroma domain which outperforms the 4:2:0/4:2:2 chroma formats of MPEG-2 and other techniques proposed in the literature. This scheme is motivated by the fact that sharp color edges and detailed areas in the color domain represent significant visual information, and therefore, require better color definition. The object-based color subsampling approach is based on segmenting the C/sub B/ C/sub R/ components of an image into high and low-activity areas. The relatively large and less informative low activity regions are decimated to one pixel while high-activity objects are preserved entirely. A fuzzy filter is incorporated in our segmentation scheme to circumvent the effect of noise which could lead to isolated pixels. The object-based approach demonstrates superior results when measured perceptually. This scheme is particularly attractive as a preprocessing step to object-based coding schemes such as MPEG-4 where segmentation can be already available for content-based manipulation and generation of hybrid video data.