Integrating the Symmetry Image and Improved Sparse Representation for Railway Fastener Classification and Defect Recognition

Table 2

The original and symmetrical distances of the samples shown in Figure 4.

Number of the subjects	Missing fastener	Worn fastener	Intact fastener
Original distance (10^5)	4.72	3.47	3.24
The first symmetrical distance (10^5)	4.93	3.55	2.76
The second symmetrical distance (10^5)	2.89	3.37	4.58