Super-resolution

Super-resolution (SR) are techniques that enhance the resolution of an imaging system. Some SR techniques break the diffraction-limit of systems, while other SR techniques improve over the resolution of digital imaging sensor.

There are both single-frame and multiple-frame variants of SR. Multiple-frame SR use the sub-pixel shifts between multiple low resolution images of the same scene. They create an improved resolution image fusing information from all low resolution images, and the created higher resolution images are better descriptions of the scene. Single frame SR methods attempt to magnify the image without introducing blur. These methods use other parts of the low resolution images, or other unrelated images, to guess what the high resolution image should look like. Algorithms can also be divided by their domain: frequency or space domain. Originally super-resolution methods worked well only on grayscale images, but researchers have found methods to adapt them to color camera images.[1] Recently also the use of super-resolution for 3D data has been shown [2]

Contents

The necessity of aliasing

In the most common SR algorithms, the information that was gained in the SR-image was embedded in the LR images in the form of aliasing. This requires that the capturing sensor in the system is weak enough so that aliasing is actually happening. A diffraction-limited system contains no aliasing, nor does a system where the total system Modulation Transfer Function is filtering out high-frequency content.

Breaking the diffraction limit

There are also SR techniques that extrapolate the image in the frequency domain, by assuming that the object on the image is an analytic function, and that we can exactly know the function values in some interval. This method is severely limited by the noise that is ever-present in digital imaging systems, but it can work for radar, astronomy or microscopy.

See also

References

  1. ^ S. Farsiu, D. Robinson, M. Elad, and P. Milanfar, "Fast and Robust Multi-frame Super-resolution", IEEE Transactions on Image Processing, vol. 13, no. 10, pp. 1327-1344, October 2004.
  2. ^ S. Schuon, C. Theobalt, J. Davis, and S. Thrun, "LidarBoost: Depth Superresolution for ToF 3D Shape Scanning", In Proceedings of IEEE CVPR 2009

Other related work

External links