Visibility Driven Contrast Enhanced Surgical Defogging

Abstract

While doing an endoscopic surgery, surgical fog is a common problem which can lead to improper device use and inaccurately targeted tissue. Defogging is the process to remove the effects of fog in captured images and reconstruct the original colour of natural scene. To address the colour infidelity problem introduced by the visibility recovery and contrast enhancement, the luminances of the recovered and enhanced images are fused in the gradient domain, and the fused luminance is reconstructed by solving the Poisson equation in the frequency domain. Contrast enhancement after fusion of images gives a result named as bilateral of bilateral filtering partially repeated (BBFPR). The fused image is given as input once again to the visibility recovery section and contrast enhancement section and fusion of images is carried once more. This gives a different output bilateral of bilateral filtering repeated (BBFR). Bilateral filtering is used to smoothen the image in visibility restoration stage. This has the advantage that it retains the edges and hence edge preservation is achieved. Moreover this method improves the speed of processing compared to median filtering. The experimental results demonstrate that the BBFR method has better contrast to noise ratio whereas BBFPR method has better naturalness and sharpness.