Fig. 1. Sea infrared images

Fig. 2. Three-dimensional map of sea infrared images

Fig. 3. SSLE

Fig. 4. The process of extracting features

Fig. 5. Fused features

Fig. 6. Two similar gray distribution of different background images

Fig. 7. Gray distribution of base layer and detail layer of different background images

Fig. 8. Local contrast calculation diagram

Fig. 9. 16*16 matrix

Fig. 10. Local contrast calculation diagram based on different sea backgrounds：

Fig. 11. Accuracy and time cost of different classification algorithms