CREDIT
First the credit i didn't use this image directlyBUT i did use its parameters that in this case is almost the same so i want thank
Andrea1981G http://andrea1981g.deviantart.com/ that shared them here
http://photocomix2.deviantart.com/favourites/#/d4qkrsecreated with M3D edited with GMIC (details below the images )
I must chose one but ,as often i have too variant and i like them all so please use the pool..1)2)3)I rendered twice bigger (3200x2400) then in gimp i used gmic to apply the graphic novel2 filter on a dup layer, dosed the opacity of the dup to fade a bit the effect
in one case i used also Gegl C2G to modify the greyscale (again i applied to a dup layer set in value mode over the original)