Essay On Speckle Noise

Abstract: In Ultrasound images, speckle noise is inherent in medical ultrasound images and it is the cause for decreased resolution and contrast-to-noise ratio. The presence of speckle noise is not attractive as it reduces the image quality and it affects the tasks of individual interpretation and diagnosis. Image variance is a granular noise that exists inherently in Ultrasound image which degrades image quality. Speckle noise reduction is one of the most important processes to enhance the quality of Ultrasound images. Before using the images of the Ultrasound for diagnosis, the first step is to reduce the effect of speckle noise. Most speckle reduction techniques have been studied by researchers; but there is no comprehensive method that takes into account all the constraints. Filtering is one of the standard methods used to reduce speckle noise. This paper compares different speckle reduction filters and presents the performance analysis to reduce speckle noise in ultrasound images in terms of the evaluation parameters of MSE, PSNR.
Key Terms: images ultrasound speckle noise, spatial domain filter, wavelet based threshold techniques, PSNR, MSE.
1. INTRODUCTION
Unlike many other imaging

Soft threshold scheme shown in Eq. (22) is an extension of hard thresholding. Discontinuities are avoided and are therefore more stable than the hard threshold. In practice, soft thresholding is more popular than hard thresholding, since it reduces the sudden abrupt changes that occur in hard thresholding and provides more visually pleasing images recovered. The goal of semi-soft threshold to offer a compromise between the hard and soft thresholding changing the gradient of the slope. This scheme requires two thresholds a λ lower threshold and upper threshold λ1 where λ1 is estimated to be twice the lower threshold value