(a) Grayscale image of gastric body mucosa taken with narrow band blue light with a central wavelength of 415 nm. (b) Grayscale image of gastric body mucosa taken with narrow band green light with a central wavelength of 540 nm. (c) Constructed color image. From Fig. 8.1a, the subepithelial capillaries (SECs) and crypt openings (COs) are colored brown, the marginal crypt epithelium (MCE) white and semitransparent, and the intervening part (IP) transparent. From Fig. 8.1b, the collecting venules (CVs) are colored cyan.

(d) Allocation to color channels and construction of a color image on the monitor. On the monitor, the images taken with 415 nm incident light are allocated to the blue and green channels, and the images taken with 540 nm incident light to the red channel. The SECs and crypt openings (COs) are well reproduced using 415 nm light. As they are expressed as a darker pattern using the blue and green channels than with the red channel, the blue/green density is decreased. As a result, elements of the remaining red channel are relatively strongly expressed, and the SECs and COs are displayed as brown (dark red) in color on a liquid crystal monitor. Vessels (CVs: collecting venules) somewhat deeper and greater in diameter than those just underneath the epithelium are well reproduced using 540 nm light. As they are expressed as a darker pattern using the red channel than with the blue and green channels, the red density is decreased. As a result, CVs are seen as a combination of the remaining green and blue channels, or cyan in color. The MCE is relatively bright with all the color channels; so in the constructed image it retains a bright pattern (white semitransparent)