A novel image retrieval approach based on the statistical model of Q-shift dual-tree complex wavelet transform(Q-shift DT-CWT) is proposed.Q-shift DT-CWT can provide a group delay of 1/4 of a sample period,and satisfy the usual 2-band filterbank constraints of no aliasing and perfect reconstruction,so it can give much better directional selectivity and shift invariance.In order to reduce dimensions,the coefficient histogram of the Q-shift DTCWT is fitted with generalized Gaussian distribution(GGD),which ove...