. Author manuscript; available in PMC: 2023 Mar 1.

Published in final edited form as: Exp Eye Res. 2022 Jan 11;216:108933. doi: 10.1016/j.exer.2022.108933

Table 2.

Possible orientation patterns based on the value of eigenvalues λ₁ and λ₂ of the Hessian matrix (Iλ₁I ≥ Iλ₂I) (Frangi et al., 1998).

λ₁	λ₂	Orientation Pattern
Low	Low	Flat or Noise no preferred direction
High−	Low	Bright tubular structure
High+	Low	Dark tubular structure
High−	High−	Bright blob-like structure
High+	High+	Dark blob-like structure