ピクセル情報の数値縮小と行列表現による内視鏡画像向けの新たな可逆情報圧縮の試み

抄録

An endoscope image has a characteristic that the image is presented by reddish colors, since much capillary vessels are located in internal walls of human organs. In the method, the image information is compressed by a characteristic of reddish endoscope image. Ordinary techniques like as DCT, DPCM are not used in the method. Compressed information is constituted by a header information section and a image construction information section. In the header information section, color numbers of each pixel are indicated by difference between its neighbor. In the image construction information section, the color number appearance rate is indicated by index symbols. The index symbols are defined as small number like 0-0, 0-1, 0-2, … in a matrix. In the experimental result, the compression rate of proposed method is not better than the case of loss-less JPEG process in large color region like a full-scaled typical endoscope images. However, the rate of the proposed method rises in small color region. Under approx. 20000 colors, the rate is better than the loss-less JPEG process. In a case of ROI#1 which is constructed by approx. 1700 colors, difference between compression rate of proposed method and the rate of lossy JPEG is less than 4%. It is considered that the proposed method is effective to compress the small color number endoscope image like as ROI image.