Infrared and Visible Image Fusion via Fast Approximate Bilateral Filter and Local Energy Characteristics

Table 1

Notation usage in the paper.

Symbol	Meaning	Symbol	Meaning
	Spatial domain		Intensity range domain
	2D function defined on		3D function defined on
	Vectors		Pixel position in 2D vector
	L2 norm		Pixel intensity at point p
	1D Gaussian:		3D Gaussian:
	Normalization factor		Standard deviation (space and range)
	The base layer with image type t		The small-scale layers with image type t (n = 1, 2, 3, 4)
	The fused image		The large-scale layer with image type t