Increasing spatial resolution by using an image sequence

• In this paper we present two methods for increasing the spatial resolution of images using image sequences where all frames contain the same static scene with unknown shifts. Because of the subpixel shifts, aliased frequencies appear in a slightly different way in all images, making it possibly to reconstruct frequencies above the Nyqvist frequency, thus improving the resolution. To this end, we estimate parameters in the affine transform relating the images to each other from the sequence. To show the applicability of the algorithms, many experiments have been carried out mainly using image sequences captured by a TV-camera and not only using synthetic image sequences. The results from one TV-camera sequence are presented in this report. Measurements of PSF and MTF have been carried out and the results show that we can increase the spatial resolution by almost a factor of two. This technique can be used for target identification/recognition as well as for visualization. The second method (interpolation) is possible to implement in real time.

Nyckelord

Image sequence

Inverse filtering

MTF

PSF

Resolution enhancement

Superresolution

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