SHAPE INFORMATION CODING AND DECODING APPARATUS FOR ADAPTIVELY BORDERING AND METHOD THEREFOR

In a shape information coding apparatus and method of bordering a binary alpha block (BAB) by pixels to construct contexts when coding binary shape information, adaptive bordering and coding of the shape information is performed in such a manner of receiving the shape information and storing a BAB; determining whether to perform frame mode coding or field mode coding based upon characteristics of the BAB; and when the frame mode coding is selected, performing frame mode bordering before performing frame BAB coding, and when the field mode coding is selected, performing field mode bordering before performing field BAB coding.