We present some fast computational methods and practical considerations for identifying cracks in a two-dimensional plate using thermal data from an infrared camera, based on the “small volume expansions” developed by Ammari, Vogelius, et. al. For an applied heat flux, the plate temperature is measured over its entire surface, so we have interior data, not just on the boundary. The novelty is that the cracks we seek are near or below the single-pixel resolution of the camera.