Estimation of muscle fiber orientation in ultrasound images after Adaptive Non-local Filtering (ANF)

In this paper, we applied the Adaptive Non-local Filtering to reduce the speckle noises and strengthen the meaningful features in musculoskeletal sonograms, then the structural features points were extracted after binarization, and finally we applied Re-voting Hough transform (RVHT) method proposed earlier to estimate the muscle fiber orientations. The results obtained by this new method was compared with those obtained using a previous method using the Sobel edge operator and RVHT only. 226 lines representing the orientation of muscle fibers or boundaries were manually selected by two operators from 45 muscular ultrasound images. These lines were also detected by the proposed automatic estimation methods. Using the results obtained manually as a reference, the differences of the new method and that using RVHT only were 0.40± 0.44 degrees and 0.70 ± 0.73 degrees, respectively. The results demonstrated that the performance of the orientation estimation method with the additional image processing approaches was fairly improved with few extra computation costs.