Sheet registration device for non-rectangular sheets

A printer comprising:

• a sheet registration device, the sheet registration device comprising:
• sensors configured for sensing relative orientations of three different edges of a sheet being transported through the registration device;
• and
• drivable steering rollers configured for re-orienting the sheet, such that one of the edges of the sheet is aligned with a predetermined alignment direction;
• and
• a controller configured to:
• determine relative angle parameters corresponding to angles between at least two different pairs of said edges from data from the sensor assembly;
• register the sheet on first and second passes using a same lateral side edge of the sheet, wherein the sheet is flipped on the second pass;
• printing a first image on a first side of the registered sheet such that the first image is printed offset by a spacing with respect to a first reference point on one of said edges;
• applying the relative orientations of three different edges to convert the spacing to offset a second image with respective to a second reference point on an edge oppositive said one of said edges on which the first reference point resides;
• and
• printing the second image on a second side of the sheet opposite the first side, wherein the second image is aligned with the first image based on the relative angle parameters by virtue of the second image being printed offset by the converted spacing with respect to the second reference point.