A Survey on Despeckling Filters for Speckle Noise Removal in Ultrasound Images

In ultrasound images, speckle noise emerges as the major cause, which has the tendency to limit the contrast resolution. This affects the detection of low contrast and small lesions. To improve clinical diagnosis, speckle reduction filters are designed to enhance the visual quality as well as preserve important features in ultrasound images. Ultrasound imaging is mainly utilized for the detection of thyroid diseases. Several despeckling filters have been proposed for the reduction of speckle noise in ultrasound images. Despecking filters are based on statistics filtering, transform domain filtering, fuzzy logic filtering and partial differential equation based filtering. This paper presents an exhaustive search in literature on the existing methods for speckle reduction in ultrasound images.