Adaptive Two-Dimensional Tree Encoding of Images Using Spatial Masking

An adaptive approach to two-dimensional tree encoding of images is presented based upon the use of spatial masking concepts. Specifically, we make use of an adaptive encoding filter of the smoothing variety whose smoothing action is controlled by the local visibility of the encoding noise. The approach is an attempt to obtain an optimum compromise between slope overload and granular noise characteristics associated with existing two-dimensional tree encoding schemes. We demonstrate that this adaptive approach can provide improved overall image coding performance, both objectively and subjectively, compared to existing tree encoding schemes at a reduced order of complexity. The subjective improvements are clear and striking to the eye.