Comparisons of detected results by ASDA under different criteria. Panels (a) and (b) show the distributions of Γ₁ and Γ₂ (backgrounds) in a 200 × 200 pixel² region of SD2. Green arrows indicate the velocity field, and the numbers label the ten synthetic Lamb-Oseen vortices. Black dots in panel (a) mark points where |Γ₁| ≥ 0.60, while black dots in panel (b) correspond to points where |Γ₂| ≥ 2/π. Panels (c) and (d) are similar to (a) and (b), respectively, but the black dots show points where |Γ₁| ≥ 0.65 and |Γ₂| ≥ 2/π, respectively. Blue and red curves in these four panels represent the boundaries of vortices rotating counterclockwise and clockwise, respectively.