BufferedImage src = ImageIO.read(new FileInputStream("Mona-Lisa-crop-256x256.png"));

        BufferedImage dest = new BufferedImage(src.getWidth(), src.getHeight(), src.getType());

        IPixIterator iPixIterator = new GilbertPixelIterator(256);

        IPixIterator destIterator = new LinearPixIterator(256, 256);

        while(iPixIterator.next()) {
            destIterator.next();
            int x = iPixIterator.getX();
            int y = iPixIterator.getY();
            int pixel = src.getRGB(x,y);
            dest.setRGB(destIterator.getX(), destIterator.getY(), pixel);
        }

:- use_module(contestlib, [writeN/2, for/3, int_width/2, write_int/2]).
spiral(N,M) :-
NM is N*M,
int_width(NM,Width),
Width1 is Width + 1,
for(I,1,N),
nl,
for(J,1,M),
distance(N,M,I,J,Distance),
write_int(Distance,Width1),
fail.
spiral(_,_).
distance(_,_,1,J,D) :- !, D is J -
distance(_,M,I,M,D) :- !, D is M +
distance(N,M,N,J,D) :- !, D is N +
distance(N,M,I,1,D) :- !, D is 2*N
distance(N,M,I,J,D) :-
N1 is N - 2,
M1 is M - 2,
I1 is I - 1,
J1 is J - 1,
distance(N1,M1,I1,J1,D1),
D is 2*N + 2*M + D1 - 4.
1 + 1.
I - 2 + 1.
2*M - J - 2 + 1.
+ 2*M - I - 3 + 1.