Tweaking The Registration

To improve the performance of the Image Registration process, I have added various changes in its structure and implementation. The addition of a user selectable blurring option was included in hopes of smoothing out the optimizer's path. I have been running the itkBinomialBlurImageFilter at twenty iterations, providing an image with its borders slightly blurred. The point set that represents the ellipse has also been shrunk to a smaller band size. Reducing the size of the ellipse band has made the metric more sensitive to every perturbation. It has resulted in the metric being very choppy. I have implemented the Registration in steps, first the translation, then the angle, and finally translation again. The first translation is allowed to move freely, with the optimizer starting at the ability to jump thirty pixels. After this is run the coordinates of the ellipse are usually in roughly the correct position. Then I run a second Registration where the angle is the parameter in question. Once that is completed, I run a third where the translation is again computed, but this time allowed an initial movement of just two pixels. This has allowed for the ability to fine tune a rough set of parameters gradually and incrementally. Although one pervasive issue throughout the process is the vacillating of the metric. It consistently is very unstable in both the translation and orientation processes.

The following is a movie of the Registration process: