Techniques for modifying data of an image that can be implemented in a digital camera, video image capturing device and other optical systems are provided to correct for non-uniform illumination appearing in data obtained using one or more illumination sources from a two-dimensional photo-sensor. In order to correct for these variations, a small amount of modification data is stored in a small memory within the optical system. According to a specific embodiment, non-uniform illumination correction factors are derived during a calibration procedure by illuminating a surface having uniform optical properties with the non-uniform illumination source and imaging that illuminated surface onto the photo-sensor.