Category	Specific Metrics
Information theory-based metric	$Q_{M I}$ : Normalized mutual information [157]
	$Q_{T E}$ : Mutual information based on Tsallias entropy [158] [159]
	$Q_{N C I E}$ : Nonlinear correlation information [160]
Image feature-based metric	$Q_{F M I}$ : Feature Mutual Information metric [156]
	$Q_{G}$ : Gradient-Based Fusion Performance [161]
	$Q_{P}$ : Image Fusion Metric-Based on Phase Congruency [162] [163]
	$Q_{M}$ : Image Fusion Metric-Based on a Multi-scale Scheme [164]
	$Q_{S F}$ : Image Fusion Metric-Based on Spatial Frequency [165]
Image structural similarity-based metric	$Q_{C}$ : Cvejie’s Metric [166]
	$Q_{S}$ : Piella’s Metric [167]
	$Q_{Y}$ : Yang’s Metric [168]
Human perception inspired metric	$Q_{C B}$ : Chen-Blum Metric [169]
Human perception inspired metric	$Q_{C V}$ : Chen-Varshney Metric [170]