Fig. 1. Traditional palm vein recognition system

Fig. 2. Proposed palm vein recognition system with pseudo image storage

Fig. 3. ROI extraction of palm vein image. (a) Original image; (b) location of ROI; (c) extracted ROI

Fig. 4. Original images and blocked images in three databases. (a) Original image in PolyU database; (b) 2×2 block image in PolyU database; (c) 4×4 block image in PolyU database; (d) 8×8 block image in PolyU database; (e) original image in CASIA database; (f) 2×2 block image in CASIA database; (g) 4×4 block image in CASIA database; (h) 8×8 block image in CASIA database; (i) ROI of original image in self-built database; (j) 2×2 block image in self-built database; (k) 4×4 block image in self-built databas

Fig. 5. Conversion between encrypted and decrypted images. (a) 2×2 blocked ROI; (b) pseudo image; (c) decrypted image

Fig. 6. Acquisition environment of PolyU database

Fig. 7. Acquisition environment of self-built database

Fig. 8. ROIs of palm vein in different databases. (a) PolyU database; (b) CASIA database; (c) self-built database

Fig. 9. ROC curve of PolyU database

Fig. 10. ROC curve of CASIA database

Fig. 11. ROC curve of self-built database