A Dynamic Color Palette for Color Images Coding

摘要

The Indexed color mode is used mainly in order to lower the number of colors and thus the need for memory space. When the RGB mode is used to describe pixel values, there are totally 16,777,216 colors for each color image; however, an ordinary color image usually does not need so many colors. Generally, 256 colors are enough for common color images; that is, it is usually more than adequate to select 256 representative colors according to the content of the image. However, some images can be so simple in color structure that not so many as 256 colors (e.g. 128 colors, 64 colors) are necessary. In this paper, we shall propose a new scheme that incorporates both CIQBM and Partial LBG. Our new scheme can dynamically adjust the number of colors needed according to the content of the image; in other words, without damaging the image quality, our new scheme will use as few colors as possible to present the color image. As a result, it will reduce the storage demand and save transmission time for images over networks.