Fig. 1. Flow chart of proposed algorithm

Fig. 2. Color correction results.(a) original images; (b) pseudo color images of original images;（c）color correction images；（d）pseudo color images based on color correction

Fig. 3. Comparison of different wavelet decomposition levels. (a) Original image; (b) level 0; (c) level 2; (d) level 4; (e) details of level 4

Fig. 4. Comparison of underwater optical image clarity effect. (a) Original image; (b) dark channel prior dehaze; (c) multiscale wavelet dehaze

Fig. 5. 2D gamma correction histogram contrast map. (a) Original image; (b) illumination component map of original image; (c) histogram before correction; (d) 2D gamma correction map; (e) illumination component map of 2D gamma correction image; (f) histogram after correction;

Fig. 6. Comparison of sharpen. (a) Original image; (b) gray scale image of original image; (c) edge detail of original image; (d) sharpened image; (e) gray scale image of sharpened image; (f) edge detail of sharpened image

Fig. 7. 2D gamma weightmap. (a) 2D gamma correction result;（b）luminance weightmap；（c）chromatic weightmap；（d）saliency weightmap

Fig. 8. Sharpen weightmap. (a) Sharpen result; (b) luminance weightmap;（c）chromatic weightmap；（d）saliency weightmap

Fig. 9. Underwater optical image enhancement results based on different algorithms. (a) Original image;（b）algorithm in reference［6］；（c）algorithm in reference［7］；（d）algorithm in reference［8］；（e）algorithm in reference［9］；（f）proposed algorithm

Fig. 10. Application test results. (a) Original image matching results; (b) enhanced image matching results

Fig. 11. Evaluation results of low illumination image

Fig. 12. Canny edge detection comparison results. (a) Original image; (b) Canny operator detection results of original image; (c) enhanced image; (d) Canny operator detection results of enhanced image