1. A display head for a graphics processor comprising: a first input path configured to propagate a first gamma-corrected pixel generated by a first graphics processor; a second input path configured to propagate a second gamma-corrected pixel generated by a second graphics processor; a pixel combiner coupled to the first input path and the second input path and configured to blend the first gamma-corrected pixel and the second gamma-corrected pixel to generate a blended pixel, wherein the blending approximates a gamma corrected blend of an external linear pixel and an internal linear pixel; and a selection circuit configured to select one of the first gamma-corrected pixel, the second gamma-corrected pixel, or the blended pixel as an output pixel, wherein the pixel combiner is configured to generate the blended pixel by computing an approximation of a gamma-corrected blend according to the formula: 
 (4 P i +4 P e +|P i −P e |)/4, where P i the first gamma-corrected pixel and P e is the second gamma-corrected pixel.