Table 1.

Comparison of the proposed method and previous methods.

Category	Restoration-Based Method	Non-Restoration-Based Method
		Single Image-Based Method		Multiple Image-Based Method
		Method	Restoration-based on optical blur caused by camera lens, and skin scattering blur by the skin layer [7].Restoration method based on de-hazing and skin scattering blur [8].	Method using gray-level grouping and a circular Gabor filter for contrast and image enhancement [10].Method using edge-preserving and elliptical high-pass filters, and histogram equalization [11].Fuzzy-based multi-threshold algorithm [12].Method using multi-channel Gabor and image reconstruction [13].	Method using optimal Gabor filter based on the direction and thickness of the vein line [6].Method using coarse vein-width variation field and primary orientation field [14].Method using vein line tracking and adaptive Gabor filtering [15].	Combination of Gabor and Retinex filters based on fuzzy theory (proposed method)
Strength	Various vein-patterns can be distinguished by removing blur effects.	The contrast between vein patterns and skin regions is increased.The proposed method is straightforward in terms of image enhancement.	Information related to the orientation and width of the vein line is considered during image enhancement.	Local and global features of a finger-vein are considered.The performance is not affected by detection errors in the orientation and thickness of a vein line.
Weakness	The direction and width of the vein are not considered during restoration. The performance can be affected by the detection of the scattering parameter.No enhancement of the recognition accuracy was demonstrated.	The direction and width of the vein are not considered. No enhancement of the recognition accuracy was demonstrated.	Detection errors in the orientation and thickness of a vein line can affect the performance.	The processing time is increased by the use of both Gabor and Retinex filters.