Algorithm 3 Testing
1:	$\mathrm{Input}: \mathrm{Low-light} \mathrm{image} X_3$$; \mathrm{optimal} \mathrm{sampling} \mathrm{step} \mathrm{size} t_{best}$$; \mathrm{velocity} \mathrm{model} v_{\theta }$$: R^d\to R^d$ with parameter $\theta$; $R$ denotes the magnification factor.
2:	$\mathrm{Sample}: X_0\sim N\left(0,1\right)$
3:	$\mathrm{Sample}: T=X_3$
4:	$X_2=v_{\theta }\left(X_0,{\rm T},0\right)+X_0$
5:	$X_t=t_{best}{X}_2+\left(1-t_{best}\right)X_0$
6:	$X_M=v_{\theta }\left(X_t,{\rm T},t_{best}\right)+X_0$
7:	$\mathrm{Return} X_M$