laser-lovers@uw-beaver (07/27/85)
From: Brian Reid <reid@Glacier> If you give the "imagemask" operator an identity matrix, then it will operate in the device coordinate system and will not attempt to do any transformations of any kind of the bits you give it. If you give it an identity matrix with an (x,y) transform component, i.e. 1 0 0 matrix= 0 1 0 x y 1 then it will still operate in the device coordinate system, but offset by x horizontal pixels and y vertical pixels. I have a vague memory that the device coordinate system as used by imagemask is upside down--that (0,0) is in the upper left corner and Y is down--but I'm not sure of it. I believe that it will also work properly with the transformation matrix mirrored horizontally or rotated 180 degrees. -- Brian Reid decwrl!glacier!reid Stanford reid@SU-Glacier.ARPA