Also tried this last night, but I honestly can't remember what I did!  Philebus is spot-on about having the right source image.  This one works quite well becasuse the main figure is so brightly-lit compared to the environment behind.  Untouched Poser render on the left - the version after a bottle of Co-Op cider* on the right!

*A cheap way of becoming intaxicated in the UK!

My self-build system - Vista 64 on a Kingston 240GB SSD, Asus P5Q Pro MB, Quad 6600 CPU, 8 Gb Geil Black Dragon Ram, CoolerMaster HAF932 full tower chassis, EVGA Geforce GTX 750Ti Superclocked 2 Gb, Coolermaster V8 CPU aircooler, Enermax 600W Modular PSU, 240Gb SSD, 2Tb HDD storage, 28" LCD monitor, and more red LEDs than a grown man really needs.....I built it in 2008 and can't afford a new one, yet.....!

My Software - Poser Pro 2012, Photoshop, Bryce 6 and Borderlands......"Catch a  r--i---d-----e-----!"