Fig. 1. Retinal image background reflective padding. （a） Sketch for the cross line between point P and O；（b） The process of copy pixel value from point Q to P； （c） Raw image and the corresponding background padded image

Fig. 2. Influence of parameter t on output Im(u)（All images are normalized to ［0，1］）

Fig. 3. Influence of parameter k on latent image

Fig. 4. Output images after intensity correction with K=15

Fig. 5. Statistical analysis for enhanced retinal image from Messidor dataset

Fig. 6. Two groups of image intensity correction

Fig. 7. Qualitatively comparison of enhanced images from different methods

Fig. 8. Enhanced images supports diagnosis of retinopathy

Fig. 9. Intensity enhancement of ultra widefield retinal image