“…Therefore, these small motions are first found in the smaller images and then are interpolated in the lower level (higher resolution) images of the pyramid until the original image is met. This method, known as optical flow, works quite well when motion is to be computed between objects, which are non-rigid, non-planar, non-Lambertian, and are subject to self occlusion, like human faces, [55], [57], [58], [71], [82], [99], [100], [115], [116], [128], [126], [176], [190], [270], [288], [295], [296], [299], [307], [414], [468], [478], [492], [500], [529], [534], [555], [592]. It is discussed in [592] that using optical flows of strong candidate feature points (like those obtained by Scale Invariant Feature Transform (SIFT)) for SR algorithms produces better results than dense optical flows in which the flow involves every pixel.…”