Tonight I've started playing around with RAW on my camera. I've used Canon's Digital Photo Professional that came with the camera to process the RAW files and I can immediately see the benefits with regards to the white balance. I deliberately took shots of my gray/white cat sat on a white/floral bedcover (I'll remove the hair later ) in horrible light.

Anyway, I've been fiddling around and so far I'm happy enough but what I can't work out is the following. I've noticed that any alterations affect the original image. Do I have to make a duplicate image before I start any work. While I don't mind fixing an image sometimes I do like to keep the crappy original for comparison.

Any other hints on using this programme?