| 摘要 |
PROBLEM TO BE SOLVED: To suppress occurrence of halation and to eliminate defective coloring, etc. SOLUTION: A wavelength calibration filter 32 is provided in between a light source filter 28 and an infrared cut filter 29, for example. When expressing the difference between the maximum value and the minimum value of the charge storage quantity of the respective color components of Ye, Cy, Mg, and G in the wavelength range of 400 to 700 nm, e.g. by a ratio to the maximum value in consideration of the spectral characteristics of a lamp 28, that of an infrared cut filter 29, that of a light guide 20, the spectral sensitivity of a CCD 24 and the spectral reflection characteristics of a normal mucosa, the difference is set to be <=0.45 by the characteristics of this wavelength calibration filter 32. Thus, a specific color is seldom saturated and the halation is reduced.
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