HYBRID MAPPING PARAMETER-ESTIMATION USING HIERARCHICAL STRUCTURE IN OBJECT-ORIENTED CODING

This paper investigates motion estimation and compensation in object-o riented analysis-synthesis coding. Object-oriented coding employs a ma pping parameter technique for estimating motion information in each ob ject. The mapping parameter technique using gradient operators require s high computational complexity.The main objective of this paper is to propose a hybrid mapping parameter estimation method using the hierar chical structure in object-oriented coding. The hierarchical structure employed constructs a low-resolution image. Then six mapping paramete rs for each object are estimated from the few-resolution image and the se parameter values are verified based on the displaced frame differen ce (DFD). If the verification test succeeds, the parameters and object boundaries are coded. Otherwise, eight mapping parameters are estimat ed in a low-resolution image and the verification test is again applie d to an image reconstructed by estimated parameters. If it succeeds, t he parameters and object boundaries are coded, otherwise, the regions are coded by second-order polynomial approximation. Theoretical analys is and computer simulation show that the peak signal to noise ratio (P SNR) of the image reconstructed by the proposed method lies between th ose of images reconstructed by the conventional 6- and 8-parameter est imation methods with reduction of the computation time by a factor of about four.