Patent ID: 7136075

Claim:
A computer program product, tangibly stored on machine readable medium, for blending a first graphic element and a second graphic element in accordance with a transfer mode, each element having a color value and an alpha, the product comprising instructions to: calculate a resulting alpha according to a first continuous function that linearly interpolates between the first element alpha and the second element alpha as a first parameter varies between 0 and 1, inclusive; calculate a second parameter, the second parameter being a ratio of the smaller of the first and second graphic element alphas and the resulting alpha; calculate an intermediate color value in accordance with the transfer mode, the color value of the first graphic element, the color value of the second graphic element, and the first parameter; and calculate a resulting color value according to a second continuous function that interpolates, as the second parameter varies between 0 and 1, inclusive, between the color of the element that has the greater alpha and the intermediate color.