Table 1.

Rational comparisons of all the employed methods in our experiments.

Name	Category			Description	Characteristic
	image based	projection based	iterative		nonlinearity data term	smoothness term
Image-based	✓			water pre-correction, FBP reconstruction, and linear decomposition
EDEC		✓		empirical calibration based polynomial decomposition and FBP reconstruction	✓
NLM	✓			water pre-correction, FBP reconstruction, nonlocal mean based smoothness, and linear decomposition		✓
WLS-NLM			✓	statistical noise property based optimization model with nonlocal mean smoothness regularization		✓
MDIR			✓	polychromatic forward projection model based iterative difference compensation method for image-based decomposition	✓
E-SART			✓	linearly approximated solution for polychromatic forward projection model	✓
Proposed			✓	polychromatic forward projection model with local linear constraint	✓	✓