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

摘要

Provided are an alpha value decision device, an alpha value decision method, a program, and a data structure of an image data capable of performing image expressions rich for both of color and transmittance while suppressing a storage volume necessary to store image data. A pixel data storage unit (32a) stores a plurality of pieces of pixel data which are respectively associated with a plurality of pixels included in an image, and indicate pixel values and indexes. An alpha value data storage unit (32b) stores alpha value data which is referred to with the indexes indicated by the plurality of pieces of pixel data in common, and indicates correspondence between the indexes and alpha values. A synthesis image generation unit (38) decides the alpha values of the plurality of pixels associated with the plurality of pieces of pixel data, respectively, on the basis of the indexes and the alpha value data indicated by the pixel data.