The 2-D directional DCT-DWT hybrid transform and its application in denoising ultrasound image

Conventional 2-D discrete cosine transform (DCT) and 2-D discrete wavelet transform (DWT) have not been taken image orientation information into account. At the same time, to remove the speckle noise in ultrasound image is also a hard nut to crack. Based on above two issues, aiming at the sectorial ultrasound image, the paper proposes directional DCT-DWT hybrid transform. The proposed rayspsila or artspsila DCT and DWT can be adopted for an image after the coordinate transform for the pixels of the image. Since the radiate wave directions are considered, the algorithm based proposed 2-D hybrid transform can inhibit the speckle noise of the ultrasound images. The experiment result verifies the proposed algorithm to be valid.