Fig. 1. Principle of the Criminisi algorithm

Fig. 2. Images before and after edge fitting. (a) Image with edge missing; (b) image with edge fitting

Fig. 3. Fitting process of the second-order Bézier curve

Fig. 4. Schematic diagram of the second-order Bézier curve

Fig. 5. Schematic diagram of Bézier curve fitting. (a) Curve before fitting; (b) curve after fitting

Fig. 6. Edge fitting experiment of damaged murals. (a) Original image; (b) mask image; (c) manually selected control point 1; (d) manually selected control point 2; (e) our algorithm

Fig. 7. Process of fusion to generate image to be repaired

Fig. 8. Repair results of different algorithms. (a) Original mural; (b) mask image; (c) Criminisi algorithm; (d) our algorithm

Fig. 9. Repair result of the real mural. (a) Original mural; (b) mask image; (c) Criminisi algorithm; (d) our algorithm; (e) local repair result of Criminisi algorithm; (f) local repair result of our algorithm

Fig. 10. Repair results of different algorithms. (a) Original image; (b) mark image; (c) X_Th = 2000; (d) X_Th = 1000; (e) X_Th = 500; (f) X_Th = 300; (g) X_Th = 200; (h) X_Th =100; (i) X_Th =50; (j) our algorithm

Fig. 11. Repair results of artificially damaged murals by different algorithms. (a) Original mural; (b) artificially damaged mask image; (c) Criminisi algorithm; (d) algorithm of Ref. [8]; (e) algorithm of Ref. [10]; (f) our algorithm

Fig. 12. Repair result of the real broken mural. (a) Original mural; (b) mask image; (c) Criminisi algorithm; (d) algorithm of Ref. [8]; (e) algorithm of Ref. [10]; (f) our algorithm