An image processing method corrects an original image. The method performs a retinex processing on a luminance signal of each pixel in an original image. The method determines, for each pixel, a retinex-processed pixel value based on the luminance signal that has been subjected to the retinex processing and at least one signal other than the luminance signal. The method generates a histogram by counting a rate of occurrence of the retinex-processed pixel values for each level over a predetermined first range of pixel values to which the retinex-processed pixel value is possibly assigned. The method reassigns each pixel value based on the histogram.