Underwater image enhancement based on red channel weighted compensation and gamma correction model
1 Key Laboratory of Adaptive Optics, Chinese Academy of Sciences, Chengdu 610209, China
2 Institute of Optics and Electronics, Chinese Academy of Sciences, Chengdu 610209, China
3 University of Chinese Academy of Sciences, Beijing 100049, China
4 Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai 264003, China
Figures & Tables
Fig. 1. Light absorption at different wavelengths underwater.
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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.
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Fig. 4. (a) Underwater image. (b) Estimated theoretical value in red rectangle. (c) RGB color cube.
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Fig. 5. (a) Original image. (b) Red channel after compensation. (c) Red channel after guided filtering. (d) New RGB image.
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Fig. 6. (a) Histogram. (b) Cumulative histogram.
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Fig. 7. Gamma correction curve.
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Fig. 8. Algorithm flow. (a) Original image. (b) After compensation. (c) γ =0.8.
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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.
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Fig. 10. Comparison of different methods. (a) Original images. (b) DCP. (c) Histogram equalization. (d) Gray World. (e) UCM. (f) Our results.
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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.
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Fig. 12. Video restoration by proposed algorithm.
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Table1. The entropy of images.
| 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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Table2. The contrast 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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Table3. Calculation time for different resolutions.
| 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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Wending Xiang, Ping Yang, Shuai Wang, Bing Xu, Hui Liu. Underwater image enhancement based on red channel weighted compensation and gamma correction model[J]. Opto-Electronic Advances, 2018, 1(10): 180024.
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