Optic Disc and Optic Cup Segmentation Methodologies for Glaucoma Image Detection: A Survey

Figure 10

The calculation process of the circular OD boundary approximation. (R) Red channel. (G) Green channel. ((R1) and (G1)) Vessel elimination. ((R2) and (G2)) Gradient magnitude image. ((R3) and (G3)) Binary image. ((R4) and (G4)) Cleaner version of the binary image. ((R5) and (G5)) Circular OD boundary approximation.