Fig. 1. Flow chart of edge contour extraction of infrared face image based on improved Canny algorithm

Fig. 2. Schematic of interpolation gradient direction in non-maximum suppression of original Canny algorithm

Fig. 3. Schematic of improved interpolation gradient direction in non-maximum suppression

Fig. 4. Comparison of image filtering processing effect

Fig. 5. Experimental results of edge contour extraction comparison from partial infrared face images

Fig. 6. Experimental results of edge contour extraction comparison from partial clipping infrared face images

Fig. 7. Comparison of quality coefficients of different edge detection algorithms for uncropped images

Fig. 8. Comparison of quality coefficients of different edge detection algorithms for clipping images