Algorithm 2 Vessel segmentation.
Input: Initial vessel layer image Iiv (a frame of S from Algorithm 1).
1:	Otsu threshold all Iivs to get binary mask MOs;
2:	Calculate the Radon-Like features of Iiv, the resulted RLF image is denoted by Riv;
3:	Phansalkar threshold Riv to get mask MP;
4:	Remove regions smaller than a fixed size ts, from MP;
5:	Take the foreground pixels in MP as seeds, do conditional dilation in MO, the result mask image is denoted by Mc;
6:	Merge the foreground regions in MP and Mc, together to get the final mask image MV.
Output: Binary vessel mask image, MV.