APPARATUS AND METHOD FOR ENCODING/DECODING IMAGE CONTAINING GRAY ALPHA CHANNEL

摘要

PROBLEM TO BE SOLVED: To provide an apparatus and method for encoding/decoding an image containing a gray alpha channel.

SOLUTION: The apparatus for encoding an image includes a block data reception unit which receives image data of a block currently being inputted to the apparatus and classifies the current block either as a foreground image portion or as a background image portion according to values of gray alpha components in the current block; a foreground image encoding unit sequentially encoding the gray alpha components and brightness and hue components of the current block if the current block is classified as the foreground image portion; and a background image encoding unit encoding the the alpha components of the gray alpha components of the current block if the current block is classified as the background image portion. The apparatus for decoding an image containing a gray alpha channel includes a bitstream interpretation unit which interprets the bitstream in units of predetermined blocks and classifies a current block obtained as one of the interpretation results either as a foreground image portion or as a background image portion.

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