Table 4.

Different methods for detection of optic disc.

Algorithm	Image processing techniques	Database	Color space	Accuracy
Rathod et al. [29]	Multilevel 2D wavelet, Histogram Equalization	HRF	Green channel	95%
Sekar and Nagarajan [30]	OD localization based on clustering and histogram approaches	Messidor	RGB	99.58%
Lu and Lim [31]	Circular transformation line operator	DIARETDB0 DIARETDB1 DRIVE STARE	CIELAB	97.4%
Acharya et al. [32]	Otsu, Gradient vector flow (GVF) snake, Atanassov Intuitionistic Fuzzy Histon (AIFSH)	Kasturba Medical College	Gray scale	100%
Trucco et al. [33]	Binary vessel masks are developed within VAMPIRE software	HRIS (High-Resolution Image Set) VDIS (Vascular Disease Image Set)	Gray scale	95.7% 92.1%