Figure 5From: An efficient approach for robust multimodal retinal image registration based on UR-SIFT features and PIIFD descriptors Distribution of features in the UR-SIFT for images of Figure 3 . (a, b) Image-space distribution (boundary points are masked) and (c, d) scale-space distribution. The UR-SIFT detects areas with densely distributed blood vessels which are robust to background changes of the retina.Back to article page