Images similarity estimation by processing compressed data

A method is proposed to evaluate the similarity of images compressed by a g iven digital wavelet transform. The method allows for comparing lossless- o r lossy-compressed images. Two features that describe the image structural content, namely edge point locations and edge density, are computed directl y from multiscale data. The distance between two images is computed in one- or two-dimensional space, depending on the image type and the choice of fe atures selected for processing. The method facilitates content-based image querying and automatic database retrieval. Additionally, images can be sort ed and appropriately indexed with respect to such characteristics as smooth ness, texture direction, repetition period and the average number of edge p oints in spatial period. (C) 2001 Elsevier Science B.V. All rights reserved .