An image processing apparatus comprising: an image input section (22, 23, 24, 25, 100) that receives a medical image picked up in a subject; a band decomposition processing section that performs decomposition processing respectively on images in a plurality of wavelength bands in the medical image, to decompose the respective images into images in a plurality of spatial frequency bands and generate a plurality of band images; an enhancement amount setting section that selects two or more band images among the plurality of band images generated by the band decomposition processing section according to an observation target existing in a depth direction of a living mucosa in the subject and sets an enhancement amount for a region where the observation target in the subject is distributed in a feature space, the feature space being a space formed so as to have, as axes, wavelength bands or spatial frequency bands of the selected two or more band images, or being another space in which the space is projected; an enhancement processing section that performs enhancement processing for increasing respective pixel values on the selected two or more band images, based on the enhancement amount set by the enhancement amount setting section; a color conversion processing section that performs color conversion processing for adjusting color tone on the plurality of band images including the selected two or more band images having been enhanced by the enhancement processing section; and an image generation section that integrates the plurality of band images subjected to the color conversion processing by the color conversion processing section, for each wavelength image, to generate an image. an image input section (22, 23, 24, 25, 100) that receives a medical image picked up in a subject; a band decomposition processing section that performs decomposition processing respectively on images in a plurality of wavelength bands in the medical image, to decompose the respective images into images in a plurality of spatial frequency bands and generate a plurality of band images; an enhancement amount setting section that selects two or more band images among the plurality of band images generated by the band decomposition processing section according to an observation target existing in a depth direction of a living mucosa in the subject and sets an enhancement amount for a region where the observation target in the subject is distributed in a feature space, the feature space being a space formed so as to have, as axes, wavelength bands or spatial frequency bands of the selected two or more band images, or being another space in which the space is projected; an enhancement processing section that performs enhancement processing for increasing respective pixel values on the selected two or more band images, based on the enhancement amount set by the enhancement amount setting section; a color conversion processing section that performs color conversion processing for adjusting color tone on the plurality of band images including the selected two or more band images having been enhanced by the enhancement processing section; and an image generation section that integrates the plurality of band images subjected to the color conversion processing by the color conversion processing section, for each wavelength image, to generate an image.