1. A computer program product tangibly embodied on a computer-readable medium, the computer program product comprising instructions operable to cause a computer to perform the operations of: performing a first search in a digital image to find candidate faces, each candidate face found in the first search being a group of pixels in the digital image that satisfies a first pattern-matching criterion; performing a second search in the digital image to find candidate eyes, each candidate eye found in the second search being a group of pixels in the digital image that satisfies a second pattern-matching criterion; performing a third search within each candidate face that includes at least one overlapping candidate eye to find red pupils, each red pupil found in the third search being a group of pixels in the digital image; and applying a color modification process to the red pupils.