Patent ID: 7035473

Claim:
A method of compressing an image comprising the steps of: (a) separating data representing said image into a plurality of image data frequency sub-bands; (b) transforming said data to a plurality of transform coefficients; (c) mapping said transform coefficients to a plurality of quantizer indices, each said quantizer index comprising a plurality of digits arrayed from a most significant digit to a least significant digit; (d) adding said most significant digits of said quantizer indices representing an image data frequency sub-band to a bitstream; (e) repeating step (d) for a less significant digit of said quantizer indices until a number of significant digits specified by a truncation limit for said image data frequency sub-band is reached; and (f) varying said truncation limit for at least two of said image data frequency sub-bands as a function of a distortion of said image, wherein the magnitude of the quantization is increased for higher frequencies relative to lower frequencies as the data rate of transmission of said image data decreases, wherein the magnitude of the quantization is decreased for higher frequencies relative to lower frequencies as the data rate of transmission of said image data increases.