Provide an image processing apparatus, a method of for operating image processing apparatus, for improve one an image processing program mucous membrane color, be likely to occur in the case where stomach is atrophy due to atrophic.It is acquired by the endoscopic image that the image signal including a narrowband image signal forms. Brightness calculates the tone and saturation of each pixel of endoscopic image. The tone H of each pixel of endoscopic image is changed to a tone H+ Δs H of the tone of the reference color far from one standard component of instruction, and the saturation S of each pixel is changed to a saturation S+ Δ S, the saturation for the reference color that the brightness of separate each pixel according to endoscopic image determines. The brightness of endoscopic image wherein each pixel is original brightness and there is a kind of color of conversion tone and saturation to be exported for it.
