Threshold-based segmentation [25] seeks to determine an intensity value, or range of intensities, which isolates a target region of interest (ROI) from a scene. Thresholding works best when the objects of interest have nonoverlapping intensities or nearly so, making possible the removal of voxels above or below a certain intensity value, called the threshold. For instance, bone is easily separated from soft tissue in X-ray CT images by thresholding manipulation. On the other hand, cerebral GM and WM in MR images, which have overlapping intensity levels, are often poorly differentiated by thresholding methods.

0 0

Post a comment