Image decoding using a shape map

An image data decoding system comprising:

• a first decoder configured to decode a coded map signal indicative of a position and shape of a content in a screen inputted for every square block of picture signals;
• a resolution transform part configured to perform a resolution transform of the map signal decoded by said first decoder;
• a second decoder configured to decode coded orthogonal transform coefficients;
• an inverse orthogonal transform part configured to perform a two-dimensional inverse orthogonal transform of the orthogonal transform coefficients;
• and
• a reproducing part configured to derive a regenerative picture signal by taking out values of pixels inside of the content from results of the two-dimensional inverse orthogonal transform by said inverse orthogonal transform part based on the resolution-transformed map signal, with respect to the blocks containing a boundary portion of the content.

A method of decoding an image data comprising:

• decoding a coded map signal indicative of a position and shape of a content in a screen inputted for every square block of picture signals;
• performing a resolution transform of the decoded map signal;
• decoding coded orthogonal transform coefficients;
• performing a two-dimensional inverse orthogonal transform of the orthogonal transform coefficients;
• and
• deriving a regenerative picture signal by taking out values of pixels inside of the content from results of the two-dimensional inverse orthogonal transform based on the resolution-transformed map signal, with respect to the blocks containing the boundary portion of the content.