Registration-Based Change Detection Charles V. Stewart Department of Computer Science Rensselaer Polytechnic Institute Change Mosaics This animation shows mosaiced and registered color fundus images of a patient with retinal vasculitis taken over a period of 2 years and 3 months. Each mosaic shows combined images taken during a single sitting. All mosaics are aligned. This allows visualization of the progress of disease. The next slide shows expanded views of five regions where changes appear to have occurred. Registration with fluorescien angiography, which we have demonstrated, is needed to confirm the significance of the changes. We are developing techniques to automatically detect and characterize changes, for use as an aid to clinical diagnosis as well as in clinical trials and reading centers. Fully automatic registration and mosaic construction make this capability possible. Expanded Views of Changes in Small Image Regions In these clipped regions of the animations (a few overlap slightly), changes appear to have occured in the position, caliber, and tortuosity of some vessels. A few vessels seem to have disappeared, although this has not been confirmed. Neovascularization around the optic disk (NVD) is apparent in the rightmost clip. Again, fully-automatic and precise alignment enables the visualization of these changes.