NOTE ON ELEMENTS OF ITERATORS/SPLITERATORS
All of the iterators/spliterators in this class implement the following paradigm:
As image implementations typically use buffers or arrays of a native datatype as a representation of their pixel values, they are not collections of a pixel datatype. The pixel datatypes used here are thus pointers into an image's array data structure. When iterating the pixel data of an image, a pixel object will be reused for each image pixel. This is done to avoid excessive allocation of pixel objects and keep the garbage collector 'asleep' (as GC heavily impacts performance). This means that the elements (pixel objects) returned by an iterator/spliterator are not distinct.