An In-field Calibrated Multiband-Multiresolution Bilateral Filter for Digital Image Applications

Abstract

This work presents the multi-band multi-resolution bilateral filter (MMBF) as a novel approach to the multi-resolution bilateral filter (MBF), which associates the bilateral filter with wavelet denoising techniques. In addition to embedding 2D-BFs in different wavelet resolutions, it also introduces one-dimensional bilateral filters (1D-BFs) in the sub-bands corresponding to the horizontal and vertical details. Developments regarding an in-field calibration method for the MMBF are also reported in order to assess its full effectiveness. The noise levels are reduced concomitantly with the preservation of edges and details, meeting the requirements of image quality. To validate the proposed method, we present a case study based on phantoms imaged by a piece of medical \mbox{X-ray} equipment. These images undergo severe degeneration when obtained under conditions of low radiation dosage. After both have been calibrated using the method proposed, the ability of MMBF to preserve image details while reducing noise surpasses the MBF by quantitative assessment as well as by visual inspection.