Abstract: When light is transmitted in water, it is severely attenuated by water absorption and scattering of suspended particles, resulting in low contrast and color distortion of underwater optical image. In this paper, a method of underwater image enhancement based on transmittance optimization and color calibration was proposed. According to the underwater optical imaging model, the transmittance was estimated based on the principle of minimum information loss, and the estimated accuracy of transmittance was improved by combining with guidance filtering. The clear underwater image was obtained by inverse solution of the underwater imaging model. The histogram equalization was utilized to further improve image contrast, and white balance method was used to calibrate color. Experimental results show that this method can effectively remove the blur caused by backscattering, improve the contrast and clarity of the image, and correct the color imbalance.

Key words: underwater image enhancement, minimum information loss, transmittance optimization, color calibration