ALPHA VALUE DECISION DEVICE, ALPHA VALUE DECISION METHOD, PROGRAM, AND DATA STRUCTURE OF IMAGE DATA

摘要

Provided are an alpha value determination apparatus, an alpha value determination method, a program, and a data structure of image data that can represent an image rich in both color and transparency while suppressing the storage capacity necessary for storing the image data. A pixel data storage unit (32a) stores a plurality of pieces of pixel data indicating a pixel value and an index and associated individually with a plurality of pixels included in an image. An alpha value data storage unit (32b) stores alpha value data that is referenced in common by the index indicated in the plurality of pieces of pixel data and that indicates correspondence between the index and an alpha value. A combined image generation unit (38) determines alpha values of a plurality of pixels associated with the respective pieces of pixel data based on the index indicated in the pixel data and the alpha value data.