Table 2. Prediction results of anthocyanin content by PCR with different preprocessing in calibration and validation sets.

Pretreatment	PCs	Calibration			Validation
		R${}_{\mathbf{cal}}^{\mathbf{2}}$	RMSEc	RPDcal	R${}_{\mathbf{val}}^{\mathbf{2}}$	RMSEp	RPDval
Raw	5	0.777	0.462	2.117	0.743	0.477	1.973
SNV	5	0.934	0.250	3.911	0.888	0.315	2.988
MSC	7	0.915	0.286	3.419	0.844	0.372	2.530
SG	5	0.776	0.463	2.112	0.741	0.479	1.965
1-Der	6	0.810	0.427	2.290	0.843	0.373	2.523
MSC+1-Der	8	0.881	0.337	2.902	0.881	0.337	2.793
SNV+BS	5	0.933	0.253	3.865	0.864	0.347	2.712
SG+1 −Der	8	0.857	0.370	2.643	0.864	0.348	2.705