Journal of Spectroscopy

Research Article

Spectral Reflectance Recovery from Tristimulus Values under Multi-Illuminants

Table 3

Statistics of the comparison results among PI, WRPCA, and the proposed method.


Method	Testing samples
	Munsell chips			ColorChecker SG			Vrhel dataset
	PI	WRPCA	Proposed	PI	WRPCA	Proposed	PI	WRPCA	Proposed

Mean RMSE	0.0095	0.0112	0.0034	0.0165	0.0296	0.0120	0.0170	0.0365	0.0152
Max RMSE	0.0714	0.0637	0.0370	0.0536	0.1361	0.0373	0.1278	0.1690	0.1454
Min GFC	0.9239	0.9088	0.9850	0.9708	0.7997	0.9803	0.9246	0.6299	0.9061
Mean GFC	0.9989	0.9983	0.9998	0.9980	0.9731	0.9988	0.9955	0.9831	0.9959
Max GFC	1.0000	1.0000	1.0000	0.9999	0.9998	1.0000	0.9999	0.9999	1.0000

CIELAB color difference under testing illuminant F2
Mean ∆E_ab	0.2520	0.3719	0.0892	0.4135	1.2824	0.2648	0.5012	1.4597	0.3547
Var.^a	0.0723	0.2046	0.0054	0.1962	1.2150	0.0403	0.2096	1.4668	0.0817
Max ∆E_ab	2.8043	4.9694	0.6701	2.7253	5.8017	1.2775	3.0989	5.3056	1.8061
%∆E_ab > 3^b	0.0000	0.6304	0.0000	0.0000	9.2857	0.0000	0.5650	13.2768	0.0000

CIELAB color difference under testing illuminant F11
Mean ∆E_ab	0.8966	1.2880	0.3095	1.3238	2.7523	0.7869	1.4677	2.7012	1.2836
Var.	0.9990	3.2857	0.0836	3.1423	4.9938	0.5667	1.9217	5.3176	1.4947
Max ∆E_ab	11.5112	28.5594	2.4955	12.7500	9.7594	3.7572	15.8069	13.1744	6.7993
%∆E_ab > 3	3.9401	8.7470	0.0000	14.2857	42.1429	1.4286	10.4520	33.6158	9.0395

^a“Var.” means the variance of the the CIELAB color difference. ^b“%∆E_ab > 3” means the percentage of testing samples with a color difference greater than 3 CIELAB units.