Adaptive-weighted bilateral filtering for optical coherence tomography

This paper presents an image enhancement method for retinal optical coherence tomography (OCT) images. Raw OCT images contain a large amount of speckle which causes images to be grainy and very low contrast. The raw OCT images thus need to be processed before any clinical interpretation is made. We propose a novel method to remove speckle, while preserving useful information contained in each retinal layer. The process starts with multi-scale despeckling based on a dual-tree complex wavelet transform (DT-CWT). Then, we further enhance the OCT image through a smoothing process that uses a novel adaptive-weighted bilateral filter (AWBF). This offers the desirable property of preserving texture within the OCT images. Glaucoma classification results confirm that our method can significantly enhance the clinical usefulness of OCT images.