1. An image correction apparatus comprising: a processor configured to: compute an absolute difference value between corresponding pixels in a first and a second image; count, within a filter region defined around an attention pixel on the first image, the number of pixels each of whose absolute difference values is not smaller than a first threshold value; compute a combining ratio of the second image to the first image so that the combining ratio decreases as the absolute difference value of each pixel contained in the filter region increases and the combining ratio when the number of pixels is not smaller than a second threshold value is lower than the combining ratio when the number of pixels is smaller than the second threshold value; and produce a corrected image by combining the value of the attention pixel in the first image with the value of the corresponding pixel in the second image in accordance with the combining ratio computed for the attention pixel and by taking the combined value as the value of the corresponding pixel in the corrected image.