The Nasa Vision Workbench library is a computer vision library / image processing library that want keep the best of the learned approach of VXL,VIGRA,GIL. So, use template and lazy evaluation to boost performance.
The new concept to use such type of library is the principle of view. You do not manipulate data directly but a view of the data. (So the view, could be a rotated, flipped, .. just by changing pixel accessor, so it do not modify input data).
The other concept that I appreciate, is an image is like a matrix, so you could perform math operation on it . I.E( img+b) -2 + atan2(imgC+imgA).
Here a good presentation of the concept :
Source : here