A Ghost in a Snowstorm

There is a storm cloud growing on the horizon of the digital convergence between computer graphics and television/graphic arts. Computer graphics and image processing assume that pixel values are linearly related to light intensity. A typical video or paint image, however, encodes intensity nonlinearly. Most image manipulation software does not take this into account and just does arithmetic on the pixel values as though they were linearly related to light intensity. This is obviously wrong. The question is, how wrong, and for what pixel values is the problem worst and best? The author presents a review of the basic concepts.