Restoration of images captured by a staggered TDI camera in the presence of mechanical vibrations

Abstract

Time Delay and Integration (TDI) sensors scan the image in one dimensions using a rectangular sensor array that integrates multiple time-delayed exposures of the same object. Due to physical constraints the TDI sensor element may have a staggered structure, in which the odd and the even sensors are horizontally separated. TDI image acquisition systems are usually employed in low signal to noise situations such as low light conditions or thermal imaging, or when high-speed readout is required. This work deals with analysis and restoration of images acquired by thermal staggered TDI sensors in the presence of mechanical vibrations. Vibrations during such an image acquisition process cause space variant image distortions in the scanning direction. These distortions include geometric warps (such as interlace comb effects) and blur. This situation is different from common case where the image degradation caused by motion is modeled as space invariant and can be treated by de-convolution techniques. The relative motion at each location in the degraded image is identified from the image using a differential technique. This information is then used to reconstruct the image using projection onto convex stes (POCS) technique. A main novelty in this work is the implementation of such methods to scanned images (column-wise). Restorations are performed with simulated images and with real mechanically degraded thermal images.