1. A method to align a first image and a second image of a subject, the method comprising: locating a sparsest blur kernel in a parameter space, the sparsest blur kernel relating a select sharp image to a select blurred image, each of the select sharp image and the select blurred image chosen from the first and second images or computationally derived from the first image or the second image; and applying an aligning operation to one or more of the first image and the second image, the aligning operation based on a location of the sparsest blur kernel in the parameter space.