Table 1 Summary of dark prior methods

θ _C

$\left({\mathbf{\text{a}}}^T\tilde{\mu }-{\left|\left|\tilde{\mu }\right|\right|}_2^2\right)/\left({\left|\left|\mathbf{\text{a}}\right|\right|}_2^2-{\mathbf{\text{a}}}^T\tilde{\mathit{\mu }}\right)$

Median operator to estimate $\tilde{\mathit{\mu }}$

θ _D

$\underset{j\in {\Omega }_i}{min}\left(\underset{c\in \left\{r,g,b\right\}}{min}\frac{{\tilde{x}}_j\left(c\right)}{a\left(c\right)}\right)$

Spectral matting

θ _F

$\frac{1}{\left|\right|\mathbf{\text{a}}\left|\right|}({\tilde{x}}_{a,i}-{\eta }_i{\tilde{x}}_{a^{\perp },i})$

Gauss-Markov random field

model

θ _T

${\text{med}}_{j\in {\Omega }_i}{w}_j-{\text{med}}_{j\in {\Omega }_i}\left|w_j-{\text{med}}_{k\in {\Omega }_i}{w}_j\right|$

None

θ _M

${\text{med}}_{j\in {\Omega }_i}\left(\underset{c\in \left\{r,g,b\right\}}{min}\frac{{\tilde{x}}_j\left(c\right)}{a\left(c\right)}\right)$

None