A linear image compositing system which corrects for nonuniform luminance and/or color of the colored backing without incurring the penalties of edge glow, edge darkening, loss of edge detail and other anomalies. A control signal is created directly proportional to the luminance of the colored backing...http://www.google.com.au/patents/US5032901?utm_source=gb-gplus-sharePatent US5032901 - Backing color and luminance nonuniformity compensation for linear image compositing
