Presentation of processing outcomes at each step before image sequence generation for subject no. 11. (a) Original image (the green channel), (b) vesselness image map obtained by scale space analysis, (c) result of 2D Gabor filtering and image segmentation, (d) the mask generated by a set of morphological operations (opening followed by five consecutive dilations), and (e) the masked vesselness image with highlighted boundaries and the main blood vessels.