.Contrast enhancement in retinal image via multi-scale geometrical analysis[J].Optoelectronics Letters,2006,2(3):229-232 Contrast enhancement in retinal image via multi-scale geometrical analysis FENG Peng PAN Ying-jun WEI Biao JIN Wei MI De-ling Department of Opto-Electronics Engineering, University of Chongqing, Chongqing 400030, China Abstract:       We present a new multi-scale geometrical analysis method for ophthalmic image contrast enhancement based on the contourlet transform. The contourlet transform has better performance in representing edges than wavelets due to its anisotropy and directionality, and is therefore well-suited for multiscale edge enhancement. We modify the contourlet coefficients in corresponding subband and take the noise into account for more precise reconstruction and better visualization. We compare this approach with enhancement based on the curvelet transform, and the traditional Histogram Stretching (HS). Our findings are that contourlet based enhancement out-performs other enhancement methods on low contrast and dynamic range images, and can clearly identify the vessels and nerves in an ophthalmic image. Hits: 3597 Download times: 186 View Full Text    Download reader