comparision of wavelet pixels

i have EEG signals on which i have done continuous wavelet transform next i m trying to compare the pixels images(present in the form of wavelet co-efficient) of two signal how do i compare them i have stored both images as jgep,whats the best way to compare them so that my information of EEG signals does not get effected, please some other methods and coding except histograms that how to compare these two images