Periodic biological functions and their related anatomy that cannot be seen in image sequences using typical means, can nonetheless be made visible by demodulating the image sequence according to the timing of that biological function using the described method. In particular, vascular structure and the function of that structure becomes observable when demodulated according to the patient's heart beat. This method suppresses the effects of thermal variations across the anatomy, and of severe scattering loss from buried tissues, that limit current thermographic (heat imaging) methods. It also measures localized changes in the wave front amplitude, shape, and phase, which are expected to prove useful for disease diagnosis and biometry.