This was done over 30 years ago (before green screen) in a lot of portrait studios with a special screen and projector. The screen was different from the usual as it was made up of thousands to tiny black glass balls that would reflect the projected light straight back at the camera (which had to be perfectly aligned with the projector and the perfectly perpendicular screen. The camera actually shot through a beam-splitter and the projector (aimed at the ceiling) bounced 90 degrees off the beam splitter to the screen.
Scene Machine was one brand: http://www.ebay.com/itm/Scene-Machine-Virtual-Backgrounds-/260834241515 If not perfectly aligned you would get a dark line around at least part of your subject. The main problem was that the studio lighting would rarely match the lighting on the background image and so would look unrealistic to the eye (which is quite good at detecting when something is not quite right). It shares this problem with green screen backgrounds of today. It was a fad that really didn't last too long (except that I see that Scene Machine is still in business, so somebody must still be buying). Darren Addy Kearney, Nebraska -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.