Blending a graphic (Patent)
A graphic and video are blended by controlling the relative transparency of corresponding pixels in the graphic and the video through the use of blending coefficients. One example of a blending coefficient is an alpha signal used in conjunction with a keyer. The value of a blending coefficient for a pixel in the graphic is based on the luminance and chrominance characteristics of a neighborhood of pixels in the video. Inclusions and exclusions are set up which define how the neighborhood of pixels is used to create or change a particular blending characteristic.
Blending a graphic (pdf)