Quantifying the parent-child coding gain in zero-tree-based coders

We attempt to quantify the coding gain due to parent-child dependencies in subband transforms. These dependencies are generally credited for the excellent mean square error (MSE) performances of zero-tree-based compression algorithms such as embedded zero-tree coding of wavelet coefficients (EZW) and set partitioning in hierarchical trees (SPIHT). Our experiments indicate that this gain is significantly smaller than what is widely believed at the time of this writing.