Noise robust local phase coherence based method for image sharpness assessment

Image sharpness assessment is a very important issue in image acquisition and processing. Novel approaches in no-reference image sharpness assessment methods are based on local phase coherence (LPC), rather than edge or frequency content analysis. It has been shown that the LPC based methods are closer to human observer assessments. In this paper, we propose carefully designed complex wavelets that provide a good tool for the local phase estimation. Moreover, we take a special care of noise. We apply thresholding in the wavelet domain and merge several estimates to achieve statistical robustness in the presence of noise. It results in the sharpness index that over-performs previously reported methods.