Aliasing effects mitigation by optimised sampling grids and impact on image acquisition chains

摘要

An insufficient sampling rate can cause the Introduction of unwanted effects in the samples of the image: the aliasing phenomenon. The aim of this paper is to investigate the possibility to mitigate the aliasing effects, trying to respect as much as possible the Shannon criteria for the image sampling. A model for the system Modulation Transfer Function (MTF) of a hyperspectral push-broom sensor is developed. Quantitative Quality Indexes are adopted in order to assess the aliasing effects on the images. By using the MTF and the Quality Indexes, the relationship between aliasing and parameters of the optical system or of the electronic apparatus will be investigated. An alternative and more effective solution could be to try to respect as much as possible the Shannon criteria. Recent Improvements in CCD technology make hexagonal sampling feasible for practical applications and bring a new interest on this topic. In our work, the advantages of hexagonal sampling with respect to conventional rectangular sampling are analysed under general assumptions. Nevertheless, using a hexagonal detector has an impact on the detection and imaging chain. In particular, processing steps must take into account the improved Sampling geometry. This leads to adaptation of existing algorithms and even new processing architectures.