An image processing apparatus includes an image acquiring unit that acquires image data about a plurality of subject images of a subject picked up under a plurality of exposure conditions different from each other; a pixel value acquiring unit that acquires, as a pixel value of a pixel position to which a spectral characteristic is to be estimated, a pixel value of the image data about any one of the subject images; an estimation operator calculator that calculates an estimation operator corresponding to the exposure condition of the subject image corresponding to the image data with the pixel value acquired by the pixel value acquiring unit; and a spectral characteristic estimating unit that estimates the spectral characteristic of the subject corresponding to the pixel position to which the spectral characteristic is to be estimated using the estimation operator calculated by the estimation operator calculator.