i see no 'right' mentioned in that description,
gimp autocrop behaves just like pike, xv cuts the left and the right side
like the result of: Image.Image(80,80,0,0,0)->box(10,10,70,70,255,0,0)->box(70,0,80,80,0,255,0)->autocrop()->autocrop()
gimp has an additional function: zealous crop, that behaves like xv.
haven't found other editors yet.
greetings, martin.