Fix image mapper positions

When images had a position other than the origin, the offset was getting
applied twice. Causing the images to be in the incorrect position. Also
cleaned up some old unused function arguments while I was in there.

Change-Id: Ie88a5c711e2d578781e2a83f89e5cc584210361e
Merge topic 'fix_image_mapper_coords' into master

25f401d4 Fix image mapper positions