Fig. 1. Feature extraction threshold and number of feature points. (a) Low illumination image; (b) normal illumination image; (c) SURF feature extraction results of normal illumination image when the threshold is 800; SURF feature extraction results of low-light image when the threshold is (d) 950, (e) 800, (f) 650, (g) 500, (h) 350, (i) 200, and (j) 50

Fig. 2. Quantitative analysis of feature thresholds and number of feature points

Fig. 3. Illumination and edge information of the image. (a) (d) Input images; (b) (e) luminance estimation images; (c) (f) edge extraction images

Fig. 4. Calculate ESR image. (a) (d) Binarized input images; (b) (e) binarized edge images; (c) (f) ESR images

Fig. 5. RMSE of Gaussian filter kernel and mean filter kernel

Fig. 6. Improved SURF low-light image stitching process

Fig. 7. Comparison of outdoor low-light image enhancement effects and enlarged details. (a) Original image; (b) SSR algorithm; (c) MSR algorithm; (d) MSRCR algorithm; (e) image enhancement algorithm in GIMP; (f) proposed algorithm

Fig. 8. Comparison of indoor low-light image enhancement effects and enlarged details. (a) Original image; (b) SSR algorithm; (c) MSR algorithm; (d) MSRCR algorithm; (e) image enhancement algorithm in GIMP; (f) proposed algorithm

Fig. 9. Feature extraction under different algorithms and thresholds. (a) Original image; (b) SURF algorithm, Hessian threshold is 800; (c) SURF algorithm, Hessian threshold is 400; (d) SURF algorithm, Hessian threshold is 100; (e) SIFT algorithm, contrast threshold is 0.06; (f) SIFT algorithm, contrast threshold is 0.04; (g) SIFT algorithm, contrast threshold is 0.02; (h) proposed algorithm

Fig. 10. Feature matching and RANSAC optimization based on fast filtering. (a) Feature rough matching results based on fast filtering; (b) feature matching results after RANSAC optimization

Fig. 11. Splicing effect of some low-light images in the data set

Fig. 12. Comparison of low-light image stitching outcomes at varying overlap rates

Table 1. Comparison of evaluation indicators of different algorithms

Table 2. Feature extraction results under different algorithms and different thresholds

Table 3. Matching algorithm performance comparison