Determination and Improvement of Spatial Resolution for Digital Arial Images

Triggered by the spread of digital aerial image acquisition, the quantification and improvement of spatial image resolution has become a topic of considerable interest for photogrammetric processing. Within our paper, the determination of image resolution based on the Rayleigh criterion and the point spread function will be discussed. These techniques then can be applied in order to exactly evaluate the quality of approaches aiming on the enhancement of image resolution. In our investigations such a resolution improvement is realised based on a linear restoring finite impulse response filter. This type of algorithm is especially suitable, if images from different camera modules are available. This will be demonstrated exemplarily using image data captured from so-called staggered arrays, which are for example available in the digital aerial camera ADS40. The improvement of spatial resolution is also applied in the context of pan-sharpening algorithms, which combine multispectral imagery with higher resolution panchromatic data. This will be demonstrated in the final part of the paper.