Author Affiliations
1Key Laboratory of Adaptive Optics, Chinese Academy of Sciences, Chengdu 610209, China2Institute of Optics and Electronics, Chinese Academy of Sciences, Chengdu 610209, China3University of Chinese Academy of Sciences, Beijing 100049, China4Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai 264003, Chinashow less
Fig. 1. Light absorption at different wavelengths underwater.
Fig. 2. The sample images.
Fig. 3. RGB channels and corresponding histogram distribution. (a) Original image. (b) R channel. (c) G channel. (d) B channel. (e) Histogram distribution of R. (f) Histogram distribution of G. (g) Histogram distribution of B.
Fig. 4. (a) Underwater image. (b) Estimated theoretical value in red rectangle. (c) RGB color cube.
Fig. 5. (a) Original image. (b) Red channel after compensation. (c) Red channel after guided filtering. (d) New RGB image.
Fig. 6. (a) Histogram. (b) Cumulative histogram.
Fig. 7. Gamma correction curve.
Fig. 8. Algorithm flow. (a) Original image. (b) After compensation. (c) γ =0.8.
Fig. 9. (a) Original image. (b) γ =0.3. (c) γ =0.6. (d) γ =0.9. (e) γ =1.2. (f) γ =1.5.
Fig. 10. Comparison of different methods. (a) Original images. (b) DCP. (c) Histogram equalization. (d) Gray World. (e) UCM. (f) Our results.
Fig. 11. Comparison of different methods of actual underwater images. (a) Original images. (b) Histogram equalization. (c) UDCP. (d) Gray World. (e) UCM. (f) Our result.
Fig. 12. Video restoration by proposed algorithm.
Images | Original image | Histogram equalization | UDCP | Gray World | UCM | Proposed algorithm | Example 1 | 6.0591 | 7.3843 | 5.6661 | 5.2953 | 6.7993 | 7.6016 | Example 2 | 6.2642 | 7.4076 | 6.0231 | 5.5167 | 6.8102 | 7.6598 | Example 3 | 6.8983 | 7.3646 | 6.3745 | 6.0943 | 6.6168 | 7.7037 | Example 4 | 6.6593 | 7.3714 | 6.2255 | 5.9450 | 6.7546 | 7.7170 | Example 5 | 6.7107 | 7.3956 | 6.3283 | 5.9642 | 6.7796 | 7.7500 |
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Table 1. The entropy of images.
Images | Original image | Histogram equalization | UDCP | Gray World | UCM | Proposed algorithm | Example 1 | 0.5296 | 1.6113 | 0.0034 | 0.6198 | 0.7179 | 1.2163 | Example 2 | 0.6092 | 1.1637 | 0.0036 | 0.7238 | 0.9214 | 1.3514 | Example 3 | 0.7225 | 1.4438 | 0.0038 | 0.8002 | 1.1921 | 1.4655 | Example 4 | 1.0048 | 1.9396 | 0.0056 | 1.2923 | 1.4122 | 1.9548 | Example 5 | 0.9635 | 1.7528 | 0.0054 | 1.1069 | 1.3013 | 1.8473 |
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Table 2. The contrast of images.
Resolution | Time/ms | Speedup ratio | CPU | CUDA | 640×480 | 324.34 | 11.15 | 29.09 | 720×540 | 381.65 | 11.60 | 32.90 | 1080×720 | 1112.09 | 21.79 | 51.04 | 1280×810 | 1547.45 | 35.01 | 44.20 |
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Table 3. Calculation time for different resolutions.