Attached Link: http://www.renderosity.com/mod/forumpro/showthread.php?message_id=2798634&ebot_calc_page#message_2798634

The extra thing you have to do for P6 (besides ticking the "Auto_fit" box), is to make sure that the "Maximum texture size" in the Render settings is set to as least as large as the largest dimension of the background image.