Patent ID: 6961097

Claim:
An apparatus for composing image data of a main picture and image data of a sub-picture by a chroma key process, comprising: attribute detecting means for detecting an attribute of an image contained in the sub-picture; area setting means for setting a partial area of the sub-picture as a chroma key mask area in accordance with an output from said attribute detecting means; and composing means for composing the image data of the main picture and the image data of the sub-picture by executing the chroma key process for an area other than the chroma key mask area without executing the chroma key process for the chroma key mask area in the sub-picture, wherein said attribute detecting means detects an attribute of an image contained in the sub-picture in accordance with addition information added to the image data of the sub-picture, and wherein the addition information includes information of a natural picture attribute described in a tag of a multimedia descriptive language.