Abstract: Underwater image pre-processing is absolutely necessary due to the quality of images captured under water. When capture such images, quality of images degrade due to many factors like ripples in water, lack of availability of light, organic matter dissolved in water etc and also such images are captured from a very small distance, so the images must be pre processed before applying any kind of operation on these images. Different filtering techniques are available in the literature for pre-processing of underwater images. The filters used normally improve the image quality, suppress the noise, preserves the edges in an image, enhance and smoothen the image. In this paper comparative analysis of various Filters for such underwater images is presented.

Keywords: Underwater image preprocessing, Homomorphic Filter, Anisotropic Filter, Wavelet filter.