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

Table 1

The decision rule for the ultimate form of original testing fastener.

The form of the first symmetrical fastener	The form of the second symmetrical fastener	The ultimate form of original testing fastener
Intact	Intact	Intact
	Partially worn	Partially worn
	Missing	Partially worn
Partially worn	Intact	Partially worn
	Partially worn	Partially worn
	Missing	Partially worn
Missing	Intact	Partially worn
	Partially worn	Partially worn
	Missing	Missing