Direction sensitive wavelet packet for despeckling of ultrasound images

Abstract

The study attempts to despeckle ultrasound images by the application of a direction sensitive wavelet packet transform. In the proposed method, wavelet packet decomposition is performed on the image and best subbands are selected using singular value decomposition. The low frequency subband is preserved, as it has the maximum information content. Iterated directional filter bank (IDFB) is applied on all other selected subbands. The vertical cells of the IDFB in the horizontal subbands and horizontal cells of IDFB in vertical subbands are eliminated because of their minimum edge information and maximum noise. Shrinkages are also applied on the remaining cells to be evaluated. The performance of the proposed algorithm is evaluated in terms of mean square error (MSE), peak signal to noise ratio, mean structural SIMilarity index, speckle suppression index, signal to MSE and speckle signal to noise ratio. It is found after the evaluation that the obtained experimental results are better than the existing state of the art despeckling techniques.

Keywords

• direction sensitive wavelet packet
• image despeckling
• ultrasound images
• singular value decomposition
• iterated directional filter bank
• mean square error