Bit-depth expansion by contour region reconstruction

Color bit-depth is an important attribute to image quality. However, the precision in various image capture devices limits the color bit-depth and introduces loss in visual quality. Expanding the color bit-depth is an important image enhancement issue. A good bit-depth expansion system manipulates low color bit-depth image for best visual quality as displayed on high color bit-depth monitors. However, in most color bit-depth expansion algorithms, severe contouring effect is observed in smooth gradient area which degrades the visual quality. In this paper, a novel approach is proposed. By considering the distance from contour edges, fine gradient value are applied to fill the contour gaps to achieve gradual transaction.