The class of two-dimensional non-separable linear canonical transforms is the most general family of linear canonical
transforms, which are important in both signal/image processing and optics. Application areas include noise
filtering, image encryption, design and analysis of ABCD systems, etc. To facilitate these applications, one need
to obtain a digital computation method and a fast algorithm to calculate the input-output relationships of these
transforms. We derive an algorithm of NlogN time, N being the space-bandwidth product. The algorithm controls
the space-bandwidth products, to achieve information theoretically sufficient, but not redundant, sampling
required for the reconstruction of the underlying continuous functions.