Low color bit-depth image enhancement by contour-region dithering

In low-end imaging systems which adopt low pixel precision, color bit-depth of an image is limited to a few bits. As a result, contouring effect tends to occur in smooth regions leading to annoying visual artifacts. Besides, the output color bit-depth is sometimes restricted in low-end systems. To enhance the visual quality in low-end imaging systems, contouring artifacts should be concealed as much as possible under the system restrictions. In this paper, a comprehensive method is proposed which combines color bit-depth expansion and dithering to enhance the image quality.