From the rotation angle and resulting DPI, it looks like it may be a sine function. Or cosine, I am not sure since the value for 45 degrees is .707 for both. Just a guess, though. If you wanted 96 DPI as the result, I would guess 74 DPI to start. The dpi ratio is consistant with the trig function. I would say if you had gotten 135 DPI, you would be at 45 Degrees. No clue why? Rich