Table 2.

The recognition rates of the compared methods.

	Euclidean-distance-based method	Metric-learning-based method
480 training, 960 testing	78.96%	86.46%
720 training, 720 testing	82.08%	91.25%
960 training, 480 testing	86.25%	92.29%
1200 training, 240 testing	84.58%	93.75%