Energy Field

The simulation returns a predicted tag profile in the direction perpendicular to image tag lines as a function of time and is normalized to lie between zero and one. To create an energy field, the following approach is taken. For points within tag lines in the the vertical orientation, a set of profiles are concatenated along the vertical axis to create a correlation kernel, . The correlation kernel is then successively rotated to create kernels along other orientations. Additional energy fields are constructed using correlation kernels for tag endpoints. Let the image be represented by . The normalized correlation, is

with , and with when is a constant multiple of . In order to increase the discrimination power of the technique the energy field is set to , where is a positive integer less than 10. Endpoint energy fields are termed , and are obtained from correlating endpoint masks with the tag data. For each tag endpoint, a correlation mask is generated, and is used to construct endpoint energy images for subsequent frames. These kernels essentially have half of the window filled with tag profiles, and depending on the tag line, have half filled with zero intensities, or intensities from surrounding organs. Currently, tag endpoint coordinates are specified in the first frame. All subsequent endpoints are determined by the algorithm.