Image Coding with Discrete Transforms using efficient energy-based adaptive zonal filtering

A. Palau and G. Mirchandani

ICASSP1994

In this paper, earlier work with adaptive zonal-coding is extended to apply to a larger class of windows that permit a better approximation of contours and adaptation to local image content. For bit allocation, we apply a variable bit-rate allocation procedure, specific to the zonal-window employed. As opposed to traditional coding schemes where bit-allocation follows block-transform coding, we develop a method where the selection of the energy/zonal-windows and bit allocation procedures proceed simultaneously. Results of both the sequential and simultaneous optimizations are presented and compared to equivalent coding of images obtained through other techniques. Including cost of bit overhead, tests show a similar signal-to-noise ratio for the same compression factor. It is also shown that our technique leads to a lowering of a local error criterion which governs detail in low intensity regions.

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