A visual aid provides utility to its users by performing geometric transformations of raw images from a digital camera into processed images for electronic display, via three nested levels of “implementation” namely, the nature of the mapping that will be applied, i.e. specifying a specific mapping or parameterized family of mappings; the algorithm set used to effect the select mapping, independent of the processor upon which it executes; and the method for realizing this algorithm on that processor. Likewise offered for consideration are software feature sets tied to user interface which enable dynamic tuning of the subject visual context and environments for low vision users, inter alia.