pub fn threshold<IM>(im: IM, op: CmpOp, thresh: u8, a: u8, b: u8) -> IMExpand description
Threshold the image so that all pixels compared with op to thresh are
set to a if true and otherwise to b.
Currently implemented only for MONO8 pixel formats.
Panics: panics if the image data is smaller than stride*height and if stride is smaller than width.