Enhancement of Underwater Images based on PCA Fusion

In Oceanic Environment, removal of hazy scenes due to the effects of scattering and absorption in underwater images plays an important issue. It is important to enhance the visual appearance of such images. In this paper a fusion based approach to enhance the underwater images is proposed. In this work, the input RGB image is subjected to Gaussian Filter and CLAHE. The RGB components applied to CLAHE are smoothened by means of median filter. The filtered RGB components are then fused using Principal Component Analysis (PCA) fusion technique. The final enhanced underwater images are subjected to both qualitative and quantitative analysis. The performance measures such as SSIM, Entropy and AMBE reveals the validation of the proposed findings. Keyword: Underwater image enhancement, Gaussian filter, CLAHE, Image fusion, Median filter. INTRODUCTION This Underwater images is affected by the color cast, poor visibility, foggy appearance and misty. Underwater images are usually degraded due to the effects of absorption and scattering. Additionally, the underwater image brings unwanted noise and increases the effects of scattering. The degree of absorption depends on different wavelengths of light (red, blue, green) which leads to the color cast of underwater images. While capturing a image of an underwater object from outside of the water, waves on the surface cause blurred. If series of images are captured at various times, different distortions will be seen in each picture. The image seen by the camera is blurred by refraction as a function of both the angle of the water surface and the amplitude of the water waves. V.Vembuselvi, T.Murugan, [1] have discussed a new method developed for enhancing the underwater images. The input image is pre-processed and convert the RGB to LAB color space. Finally, LAB color space is convert into the RGB color space. Ritu Singh, Dr.Mantosh Biswas, have discussed a new method developed for enhancing the underwater images. In this paper, the fusion technique based on hazy image to improve the quality of degraded underwater images [2]. The contrast limited adaptive histogram equalization (CLAHE) technique is used to enhance the underwater image by Dithee Dev K, Mr. S.Natrajan [3]. Ashish Gupta, J Sandesh.et al have discussed a new image enhancement method is developed for better visual quality. In this paper, the input RGB image is converted into HSV format. Then split the individual H, S and V component. And apply Histogram Equalization method for Saturation component. The histogram of a digital image gives conclusive proof about the quality of the image. After the Histogram Equalization technique, concatenated the H, equalization method and V component. Then convert these HSV component into RGB component. Finally, the output image is better than the input image [4]. R. Priyadharsini,T. Sree Sharmila et al have worked in Stationary Wavelet Transform (SWT) with laplacian filter. The Laplacian filter is applied on LL component and subtracting the LL component with the filtered image we get one mask image[5]. Ansar MK, Vimal Krishnan VR research has been carried out in underwater image enhancement by using PCA fusion is proposed by [11]. Jasneet kaur Babool, Satbir Singh have discussed a contrast limited adaptive histogram equalization color models for enhancing the underwater images[12]. Joost van de Weijer, Theo Gevers et al researcher work is based on color constancy. Color constancy is the ability to measure the colors of the light source [13]. Codruta O. Ancuti , Cosmin Ancuti, in this paper, Adaptive Histogram Equalization based Fusion Methods are developed to enhance the underwater images [14]. Yafei Wang, Xueyan Ding et al , the proposed fusion process involves two inputs which are represented as color corrected and contrast enhanced images extracted from original underwater image [15].