Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
Preprocessing. (a) Original color image; (b) detected optic disc center in black “+”; (c) extracted ROI; (d) blood vessels extraction; (e) “vessels-free” image; (f) red channel of (e). Blue: the extracted optic disc initialization contour and green: the extracted optic cup initialization contour.
