The application of inverse filters to 3D microscanning of LADAR imagery

Microscanning is an effective technique for reducing aliasing and increasing resolution in 2D images produced by non-coherent imaging systems. Both the aliasing reduction and resolution enhancement are accomplished by increasing the effective spatial sampling interval through sub-pixel movements of the field of view on the detector array. In this paper the authors examine (using both simulated and real data) the application of microscanning on 3D coherent imagery (with application to 2D coherent imagery). The application of inverse filtering techniques are also examined to resolve difficulties associated with blurring by the detector and optical systems. The effects of blurring by the detector and optical system decrease image resolution when microscanning is attempted at sub-pixel movements of less than half the detector width. A discrete filter is designed using the MTF of the imaging system. This filter is then applied to images collected with a 128times128times20 FLASH 3D LADAR system. The authors also investigate the difficulties that arise when the MTF of the system is not well characterized and when image registration errors and a low signal to noise ratio are present in the system