TABLE 4. Average PSNR, SSIM, and IFC of Resolution-enhanced Virtual Phantom Images.

Metric	Data-set	Scale	SRCNN [10]	FSRCNN [11]	DRCN [12]	ACNS
PSNR (dB)	1		26.70 ± 1.55	26.54 ± 1.27	24.40 ± 1.38	27.01 ± 1.50
			25.68 ± 2.25	24.56 ± 1.33	25.21 ± 1.34	24.80 ± 1.38
			24.10 ± 1.97	23.29 ± 1.28	27.49 ± 1.23	23.86 ± 1.35
	2		28.52 ± 0.82	28.03 ± 0.71	25.67 ± 1.07	28.84 ± 0.96
			26.41 ± 0.88	26.17 ± 0.78	26.31 ± 1.10	26.73 ± 0.98
			25.01 ± 0.92	24.97 ± 1.28	29.19 ± 0.93	25.85 ± 1.04
	3		28.87 ± 1.55	28.36 ± 0.57	25.58 ± 0.88	29.10 ± 0.70
			26.66 ± 2.25	26.53 ± 0.64	26.69 ± 0.66	26.74 ± 0.71
			25.28 ± 1.97	25.15 ± 1.28	30.05 ± 0.84	25.88 ± 0.73
SSIM	1		0.88 ± 0.04	0.63 ± 0.10	0.88 ± 0.03	0.83 ± 0.01
			0.84 ± 0.07	0.59 ± 0.07	0.91 ± 0.03	0.82 ± 0.05
			0.77 ± 0.09	0.54 ± 0.06	0.93 ± 0.01	0.76 ± 0.06
	2		0.92 ± 0.01	0.47 ± 0.02	0.92 ± 0.01	0.84 ± 0.01
			0.87 ± 0.02	0.46 ± 0.01	0.93 ± 0.01	0.88 ± 0.02
			0.82 ± 0.02	0.43 ± 0.06	0.95 ± 0.01	0.85 ± 0.02
	3		0.93 ± 0.04	0.42 ± 0.02	0.93 ± 0.01	0.84 ± 0.00
			0.89 ± 0.07	0.42 ± 0.02	0.94 ± 0.01	0.89 ± 0.01
			0.85 ± 0.09	0.39 ± 0.06	0.96 ± 0.01	0.86 ± 0.01
IFC	1		4.34 ± 0.78	4.44 ± 0.81	3.37 ± 0.67	4.77 ± 0.89
			2.80 ± 0.40	2.92 ± 0.48	3.07 ± 0.75	3.01 ± 0.53
			1.89 ± 0.26	1.93 ± 0.30	3.00 ± 0.72	2.08 ± 0.34
	2		2.92 ± 0.23	2.93 ± 0.24	2.22 ± 0.18	3.19 ± 0.23
			1.88 ± 0.13	1.98 ± 0.15	2.24 ± 0.19	2.07 ± 0.13
			1.32 ± 0.09	1.33 ± 0.30	2.16 ± 0.15	1.46 ± 0.09
	3		2.66 ± 0.78	2.67 ± 0.23	1.93 ± 0.20	2.76 ± 0.25
			1.80 ± 0.40	1.89 ± 0.17	2.04 ± 0.21	1.81 ± 0.16
			1.29 ± 0.26	1.30 ± 0.30	1.99 ± 0.19	1.32 ± 0.11