Patent ID: 6125201
Filing Date: 2000-09-26
Classification: H04N

Abstract:
A method of compressing a digital image to obtain a compressed image data set for subsequent reconstruction, comprising the steps of:(i) determining if the digital image is a color image in RGB color space and converting any determined RGB color images to a less redundant color space;(ii) performing a wavelet decomposition upon each of the color planes of the image in said less redundant color space to obtain a transform of DC and non-DC terms;(iii) lossless coding the DC terms;(iv) converting the transform to sign and magnitude format and selecting a division point comprising one of an adjacent pair of bit-planes and a pair of adjacent amplitudes, which separate the non-DC terms into first and second ranges based upon absolute magnitudes, the first range comprising the values of the transform which are greater in magnitude than those values in the second range of the transform;(v) employing a scalar quantizer to encode the values in the first range;(vi) employing a vector quantizer to encode the values in the second range; and(vii) coding the resulting data set with a lossless entropy encoder to obtain a compressed image data set.