Usage: sub in1.pgm in2.pgm out.pgm
Description: For each pixel x, out[x] = in1[x] - in2[x]. For byte and long image types, if out[x] < 0, then out[x] is set to 0. Images must be of the same type and same dimensions.
Types supported: byte 2d, byte 3d, long 2d, long 3d, float 2d, float 3d
Category: arith
1.2.18