A computerized fluoroscopy system which was recently developed in our laboratories permits image contrast increases of 8-16 relative to conventional image intensifer fluoroscopy and permits study of canine and human ventricular wall motion using peripheral intravenous injections. Two time-dependent image subtraction algorithms are illustrated in connection with observation of artificially infarcted dog hearts. The first algorithm produces a display analogous to direct ventriculography using catheterization. The second displays regions of dyskinetic motion as anomalous image grey shades.