An efficient lapped orthogonal transform image coding technique

A fast and computationally less complex coding technique is described which uses partial-lapped orthogonal transform (LOT) computation algorithm and efficiently discards perceptually insignificant high frequency transform coefficients. The coding process involves activity class energy classification, human visual system weighted normalization and quantization. The values of normalization factors are image independent and governed only by the bit-rate and activity index of the image blocks. Zones of various shapes and sizes are chosen for each activity class to perform zonal sampling which efficiently discards high frequency coefficients having zero values. A progressive transmission version of the proposed technique is also given. This technique gives better performance at comparable bit-rate than that obtained by using LOT/CVQ and LOT/VQ schemes