Comparative Evaluation of Anisotropic Filters Used to Reduce Speckle in Ultrasound Images

Image denoising in medical image processing is essential to improve the visual quality of the image and, consequently, the diagnosis. Speckle, a multiplicative noise that degrades the image, is common in ultrasound imaging as it tends to degrade the resolution and contrast in the image. Several filters have been developed to reduce this kind of noise. This paper presents a comparative evaluation of some anisotropic filters used to reduce the speckle noise in ultrasound images. The evaluated filters were Coherence-Enhancing Diffusion (CED), Speckle Reducing Anisotropic Diffusion (SRAD), Detail-Preserving Anisotropic Diffusion (DPAD), and Anisotropic Diffusion Filter with Memory Based on Speckle (ADMSS). The filters processed four phantom ultrasound images with speckle noise. The comparison performances of filters occurred by using Mean Square Error, Signal to Noise Ratio, Peak Signal Noise Ratio, and Structure Similarity Index. The results showed that ADMSS better reduces speckle noises in ultrasound images, compared to the other filters evaluated.