摘要 |
A subject is simultaneously exposed to broadband light (BB) and narrowband light (NB). Said subject is imaged using a color CCD (33), yielding a blue signal (B), a green signal (G), and a red signal (R). A base image is generated from said signals (B, G, and R), and a B/G image is generated from the B/G ratio, i.e. the ratio of the blue signal (B) to the green signal (G). Pixels representing B/G ratios less than or equal to a mucous-membrane/superficial-blood-vessel boundary value (Ls) are extracted from the B/G image, yielding an image containing extracted superficial blood vessels, and pixels representing B/G ratios greater than or equal to a mucous-membrane/mid-depth-blood-vessel boundary value (Ld) are extracted, yielding an image containing extracted mid-depth blood vessels. Said boundary values (Ls and Ld) are different for each observation mode. |