FIGURE 4.

Feature extraction with superpixels. We extract six ratios to construct a feature vector from each superpixel. These ratio ultimately quantify shape, position and orientation of the specific super pixel. Training labels are generated based on the degree of overlap between a specific superpixel and manually labeled vertebral segments. When there is no overlap between a superpixel with any manually segmented vertebral region, the label corresponding to the feature extracted from the superpixel is 0, otherwise it is 1.