Human visual weighted quantization for transform/subband image coding revisited for interlaced pictures

The paper addresses the problem of human visual weighted quantization for transform/subband coding of interlaced pictures. This problem has been correctly solved for progressively scanned pictures [Vandendorpe 1991]. When interlaced pictures are coded, the problem can be solved easily for field coding. However, if the coding of merged fields (known as frame coding) is preferred, the quantizer optimization becomes more difficult. In the paper, the authors show how to solve the problem for merged field coding by using the motion information which exists between 2 successive fields. The weighting factors required to determine the quantization step sizes of the subbands are shown to be dependent on this motion information. In addition, the variances of the subbands produced after held merging are also dependent on the motion. Their exact expression is derived