Cross processing is the procedure of deliberately processing photographic film in a chemical solution intended for a different type of film. The effect was discovered independently by many different photographers often by mistake in the days of C-22 and E-4. The process is seen commonly used in fashion shoots, advertising, by photographers shooting rock bands. In more recent years has become associated with the Lo-fi photography movement.
It’s fairly easy to emulate digitally using a Photoshop action or with http://www.fotoflexer.com or a similar site online. I snapped the young lady in the photograph above at the resurrected Strawberry Fair (2011) in Cambridge, she was a marshall (I believe) watching a young band perform on the steam-punk stage, her “tempus fugit” hair band fitted the scene perfectly. A mutual friend of a Facebook friend tagged her in my Strawberry Fair 2011 album, but I shall spare her blushes and not name her here. I applied the Fotoflexer cross processing effect and then a limited amount of the Lomo effect just for fun. You can see the original version of the photo in my gallery on Facebook.