Patent ID: 7554554

Claim:
A rendering apparatus that blends a plurality of source images into a destination image stored in a frame buffer and renders a blended image of the source images and the destination image on a display, comprising: a temporary memory of higher speed and smaller capacity than the frame buffer; a calculating unit that calculates a first data and a second data without using the destination image and stores the first data and the second data in the temporary memory; and a blending unit that blends the source images into the destination image using the first data and the second data stored in the temporary memory to obtain the blended image, and stores the blended image in the frame buffer, wherein the calculating unit includes a first subtracter that subtracts a color code C t , which is the first data previously calculated and stored in the temporary memory, from a color code C of one of the source images; a first multiplier that multiplies an output of the first subtracter by a blend ratio α of the source image; an adder that adds the color code C to an output of the first multiplier; a second subtracter that subtracts the blend ratio α from 1; and a second multiplier that multiplies an output of the second subtracter by a blend ratio α t , which is the second data previously calculated and stored in the temporary memory, and the calculating unit overwrites the color code C t by an output of the adder and overwrites the blend ratio α t by an output of the second multiplier.