Lapped orthogonal transform designed for error resilient image coding
This paper describes a new design method for lapped orthogonal transforms (LOTs) that can provide a desired trade-off between coding efficiency and robustness to transmission errors. Traditionally, the LOT bases were designed to maximize the coding efficiency solely. When certain coefficients are lost due to impairments in the transmission channel, these bases often provide unsatisfactory reconstruction quality. In our previous work, we have developed a new reconstruction method, the maximally smooth recovery (MSR) method, which can achieve better image reconstruction quality from incomplete LOT coefficients than simple interpolation methods. We present a new LOT basis design method, which maximizes a weighted average of a coding gain and a reconstruction gain, with the latter being defined according to the MSR method. We show that these new bases can achieve significantly better redundancy-rate-distortion (RRD) performance than the set of basis designed by Hemami (1996).