Fig. 3
A crop of the vessel annotation of FOVEA003_p by annotator 1, demonstrating the post-processing of raw annotations. (a) The raw vessel annotation in red, showing different intensities due to the pressure-sensitive nature of the Apple pencil used. (b) The raw annotation thresholded using a value of 0.5. While perfectly viable for the larger vessels, it leaves the thin vessel in the middle fragmented - eliminating small isolated areas of annotation would delete this entire vessel branch. (c) The skeleton of the mask obtained from thresholding the raw annotation with a value of 0.1 overlaid on to the middle image. The skeleton pixels serve to close the gaps and will preserve the continuity of the vessel tree.
