New padding method for arbitrarily shaped image coding

MPEG-4, with its superior compression, interactivity and universal access, is the most promising future standard. MPEG-4 relies on a content-based representation so it can provide new functionalities such as content-based interactivity and scalability. Content-based coding, which encodes the objects within a picture, is one ofthe most important functionalities proposed by MPEG-4, and it has attracted considerable attention. Moreover, encoding the texture ofan arbitrarily shaped object is an important part ofobject-based coding. Therefore, many researchers have being trying their best to solve this problem, and they proposed various methods to encode the texture ofan arbitrarily shaped object. In this paper, we summarize several methods of arbitrarily shaped object coding including SA-DCT (Shape Adapted-DCT), EA-DCT (Expanded Arbitrary-Shaped DCT), Mean Replacement Padding and Low Pass Extrapolation Method (LPE). We also propose two new padding method ofarbitrarily shaped object coding. Experimental results showed that the proposed methods have almost the same effect as LPE method, which MPEG-4 has adopted, so that it can improve the coding efficiency of DCT.