AN IMAGE DATA ENCODING SYSTEM

摘要

An image data encoding system efficiently reconstructs an image through a progressive image buildup in stages. An original image is divided into blocks each having NXN picture elements, whose transformation coefficients are obtained by orthogonal transformations on their graduated values. The image data encoding system has a transformation coefficient memory (61) for storing transformation coefficients; a mask information memory (62) for storing mask information for masking transformation coefficients; a masker (63) for masking the most significant bits of the transformation coefficients specified by mask information; a shift information memory (72) storing quantization thresholds for quantizing the transformation coefficients; and a quantizer (65) for quantizing the masked transformation coefficients per the quantization threshold. The quantization threshold can be given a value of 2 to an integer power, and quantization can be attained by shifting bits of the transformation coefficients towards less significant bits by that power. <IMAGE>