[OPTICAL REVIEW Vol. 5, No. 6 (1998) 352-357]

Topographic Measurement of Internal Surfaces Using a Sequence of Stereo Charge-Coupled Device Endoscopic Images: (1) Method

Shin-ichiroh KITOH,1 Hiroki TOKUOKA,1 Jun HASEGAWA,2 Tetsuo NONAMI,2 Takashi OBI,1 Masahiro YAMAGUCHI1 and Nagaaki OHYAMA1,*

1Imaging Science and Engineering Laboratory, Tokyo Institute of Technology, 4259, Nagatsuta, Midori-ku, Yokohama, 226-8503 Japan, 2Olympus Optical Co., Ltd., 2951, Ishikawacho, Hachioji, Tokyo, 192-0032 Japan

(Received January 21, 1998; Accepted August 24, 1998)

In endoscopic diagnosis, there has been a strong requirement to measure the internal surface topography of the rectum or esophagus. Accurate measurement, however, is very difficult, because the object is usually observed from an inclined view. In this paper, we propose a method to overcome this difficulty utilizing sequential stereo-pair images; the relative shape is roughly measured from sequential images taken by one of the change coupled device (CCD) cameras, and the size is determined by stereo-pair matching using the measured shape. A coarse-to-fine approach is also used to improve the resolution of topographic measurement. Through a basic experiment using a monocular CCD endoscope and a polyp phantom, the proposed method is confirmed to improve measurement accuracy in comparison with conventional methods.

Key words : stereo CCD endoscope, topographic measurement, image sequency, stereo matching, disparity, inclined view, gastrointestinal surface

* yama@isl.titech.ac.jp