Acoustic image denoising using various spatial filtering techniques

Abstract

Sonar, the instrument used for acquiring underwater acoustic images strongly participate in the assistance of detection and recognition of objects under the seafloor. Sonar emits sound waves to navigate deep into the sea and detects the sunken objects. The sonar images are also used for fish habitat mapping. Noise is an important factor that contributes to the degradation of quality of the images obtained by sonar. Generally speckle noise is found in the acoustic images which are caused by the instruments that affects the quality, thereby reducing visual perception. In this paper, various spatial filtering techniques have been applied to the acoustic images to remove the speckle noise. Among the filtering techniques available, bilateral filter followed by guided filter, when applied to the acoustic images tend to remove the speckle noise to a greater degree. The statistical methods for image quality assessment such as mean squared error (MSE), peak signal to noise ratio (PSNR), Structural SIMilarity Index (SSIM) are used to compare the quality of the despeckled images.