Table 1.

Description of different approaches and parameter settings used for $OF$ evaluation on Hydrangea images with brightness change.

Approaches	Descriptions and Parameter Settings
HS	Classical H&S method, $\lambda =1000$.
HS + IN	H&S method with Intensity Normalization, $\lambda =1000$.
HS + BR	H&S method with Brightness Relaxing factor, ${\lambda }_s=10,{\lambda }_{sc}=1,{\lambda }_{tc}=1$, and d = 0.35.
the enhanced OF algorithm	combine HS+BR and intensity normalization.