Subspace-based methods for image registration and super-resolution

Abstract

Super-resolution algorithms combine multiple low resolution images into a single high resolution image. They have received a lot of attention recently in various application domains such as HDTV, satellite imaging, and video surveillance. These techniques take advantage of the aliasing present in the input images to reconstruct high frequency information of the resulting image. One of the major challenges in such algorithms is a good alignment of the input images: subpixel precision is required to enable accurate reconstruction. In this paper, we give an overview of some subspace techniques that address this problem. We first formulate super-resolution in a multichannel sampling framework with unknown offsets. Then, we present three registration methods: one approach using ideas from variable projections, one using a Fourier description of the aliased signals, and one using a spline description of the sampling kernel. The performance of the algorithms is evaluated in numerical simulations.

Super-resolution: a comprehensive survey

“…This method is shown to be able to handle multiple motions in the input images [368]. - [370] Fourier description-based registration has been used. - [371], [422], [592], [615] Each motion model has its own pros and cons.…”

“…In addition to the above mentioned methods in the frequency domain, some other SR algorithms of this domain have borrowed the methods that have been usually used in the spatial domain; among them are: [119], [211], [321], [370], [589] which have used a Maximum Likelihood (ML) method (Section 5.1.5), [144], [178], [201] which have used a regularized ML method, [197], [221], [267], [491], [511], [567] which have used a MAP method (Section 5.1.6), and [141], [175] which have implemented a Projection Onto Convex Set (POCS) method (Section 5.1.4). These will all be explained in the next section.…”

Image registration under arbitrarily-shaped local illumination variations

“…If one of these two steps is inaccurate, the resulting HR image will be degraded, and no gain in actual resolution may result. Readers can be referred to some of the presented SR techniques in [72,74,75,[88][89][90][91][92][93][94][95][96][97][98]].…”