1. A method for generating composite images, comprising the steps of: (a) generating data of a first source image with a first image generator; (b) generating data of a second source image with a second image generator; (c) transmitting data of said first source image to a frame buffer in accordance with a first mask; and (d) transmitting data of said second source image to said frame buffer in accordance with a second mask, wherein: said first source image comprises a plurality of first-image pixels; said second source image comprises a plurality of second-image pixels; said first mask comprises a plurality of first-mask pixels, each of said first-mask pixels having a corresponding value and each of said first-mask pixels corresponding to one of said first-image pixels; said second mask comprises a plurality of second-mask pixels, each of said second-mask pixels having a corresponding value and each of said second-mask pixels corresponding to one of said second-image pixels; step (c) comprises the step of transmitting each of said first-image pixels having a corresponding first-mask pixel of non-zero value; and step (d) comprises the step of transmitting each of said second-image pixels having a corresponding second-mask pixel of non-zero value.