Research On Color Correction And Clarification Methods For Underwater Images

Nowadays,the rapid expansion of the earth’s population,the increasing shortage of land resources,and the gradual deterioration of the natural ecological environment have prompted people to focus their development attention on the ocean.The area of the ocean accounts for71% of the earth’s surface area,underwater optical image detection technology is an important technology for marine development and detection,underwater images play an important role in marine resource exploration,marine biological research and marine military applications.Underwater images have richer color information than acoustic images,and these color information can become information that intuitively reflects the characteristics of objects,guiding the identification and classification of underwater objects.Because light is generally affected by water absorption and scattering when traveling underwater,light gradually attenuates with the extension of wavelength and deepening of water depth,and finally causes blurred underwater images,especially color deviations.Therefore,it is necessary to make color compensation correction for underwater images,and adopt effective image clarity methods to improve the quality of underwater images.The main research contents of this study are as follows:(1)Aiming at the problems of color deviation and atomization of underwater images,an underwater image enhancement algorithm based on Laplace pyramid fusion is proposed based on the actual situation.The whole algorithm mainly contains two parts: one is the underwater white balance method,which uses the improved underwater white balance to reduce red artifacts,and reduces the attenuation of light underwater for the purpose of removing color deviation.The other part uses the LAB and RGB color spaces to enhance the contrast of the global histogram stretch,non-uniform filtering to reduce image noise,combine homomorphic filtering to enhance the dark details of the image,and use the Laplace pyramid to fuse the two images with different weights to improve the contrast and saturation of the underwater image,and eliminate the image fogging surface under the influence of scattering.After experimental results,the average index value of UIQM increased by 10.87% after processing,and the average index value of UCIQE was higher than that of other algorithms.The algorithm in this thesis can effectively improve the clarity of underwater images,and the images with enhanced color and contrast have high visual perception quality,which can better conform to the subjective perception of the human eye.(2)Aiming at a series of problems such as color distortion,image blur,low contrast and noise interference of underwater images,this thesis proposes an underwater image enhancement algorithm based on color equalization and multi-weight fusion.The algorithm first uses the dark channel prior(DCP)algorithm for water blur preprocessing,and then uses the automatic white balance algorithm based on dynamic threshold for color shift correction,and then performs multi-weight fusion of the processed image.The fusion process is mainly based on the weight calculation of two images,namely the contrast-enhanced image based on gamma correction and the edge-enhanced image based on histogram equalization,and then the significance weight and saturation weight of the two maps are calculated respectively,and finally the weights calculated by linearly fusion of the two maps are obtained by the enhanced image.The results show that the overall clarity recovery effect of underwater images after the algorithm processing is better,and the contrast and image color details are greatly improved,and compared with other mainstream algorithms,the objective evaluation indicators UCIQE and UIQM have a significant improvement effect,and the average parameter indicators are improved by about 22.3% and 10.2%,respectively.After laboratory evaluation and analysis such as noise performance evaluation,subjective performance comparison,and objective performance comparison,qualitative and quantitative evaluation methods are integrated,and the effectiveness of the method is finally verified.The color compensation and correction method for underwater images proposed in this thesis has high image clarity,and can be used in foggy weather and sandstorm images in addition to marine exploration,and has wide applicability.