An image processing apparatus comprising: an image obtaining unit that obtains a plurality of frames of the same scene in which a water quality examination target including a water surface having a wave is captured, each frame including a first image , a second image , and a third image , the first image being an image based on a first wavelength range, the second image being an image based on a second wavelength range different from the first wavelength range, and the third image being an image based on a third wavelength range which includes the first wavelength range and the second wavelength range; a pixel value obtaining unit that obtains a pixel value at a given pixel position (P) in each of the third images of the plurality of frames ; a proportion or difference calculation unit that calculates a proportion or a difference between the pixel value of the first image and the pixel value of the second image corresponding to said pixel position (P) in the frame where the obtained pixel value at said pixel position (P) is the minimum among the plurality of frames; a storage unit that stores the proportion or the difference calculated by the proportion or difference calculation unit; a water quality data calculation unit that calculates water quality data of the water quality examination target based on the proportion or the difference stored in the storage unit; and a water quality distribution image generation unit that generates a water quality distribution image showing a water quality distribution of the water quality examination target based on the water quality data calculated by the water quality data calculation unit. an image obtaining unit that obtains a plurality of frames of the same scene in which a water quality examination target including a water surface having a wave is captured, each frame including a first image , a second image , and a third image , the first image being an image based on a first wavelength range, the second image being an image based on a second wavelength range different from the first wavelength range, and the third image being an image based on a third wavelength range which includes the first wavelength range and the second wavelength range; a pixel value obtaining unit that obtains a pixel value at a given pixel position (P) in each of the third images of the plurality of frames ; a proportion or difference calculation unit that calculates a proportion or a difference between the pixel value of the first image and the pixel value of the second image corresponding to said pixel position (P) in the frame where the obtained pixel value at said pixel position (P) is the minimum among the plurality of frames; a storage unit that stores the proportion or the difference calculated by the proportion or difference calculation unit; a water quality data calculation unit that calculates water quality data of the water quality examination target based on the proportion or the difference stored in the storage unit; and a water quality distribution image generation unit that generates a water quality distribution image showing a water quality distribution of the water quality examination target based on the water quality data calculated by the water quality data calculation unit. <EOS>