Patent ID: 6434273
Filing Date: 2002-08-13
Classification: G06T

Abstract:
A method for generating a higher quality reconstructed image from a starting image resulting from a compressed representation of a bi-level image, comprising the steps of:decompressing the compressed representation to produce the staring image; thresholding to force pixels of the starting image to be closer to bi-level to generate a threshold image; transforming the threshold image to generate transform coefficients representing decomposition of the threshold image; selectively clamping a portion of the transform coefficients into quantization bins defined by compression of the bi-level image, the selective clamping generating modified coefficients corresponding to the higher quality reconstructed image; and applying an inverse transform on the modified coefficients to generate the higher quality reconstructed image, the thresholding comprising the substeps of: selecting a random number between zero and one for each of the pixels; defining a probability function that specifies the probability that each pixel of the staring image will be forced to be a first color; setting a first portion of the pixels to the first color if the probability function for each of the pixels in the first portion of pixels is not less than the corresponding random number; and setting remaining pixels to a second color if the probability function for each of the remaining pixels is not less than the random number.