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 Image image shading variations appearing in data from a two-dimensional photo-sensor. These variations can be caused by imperfect lenses, non-uniform sensitivity across the photo-sensor, and internal reflections within a housing of the optical system, for example. In order to correct for these variations, a small amount of modification data is stored in a small memory within the camera or other optical system, preferably separate correction data for each primary color. Image data from individual pixels are corrected on the fly by interpolating individual pixel corrections from the stored modification data, at the same rate as the image data is being acquired, so that the correction takes place without slowing down data transfer of picture data from the image sensor.