I should know how to do this, but i can't remember. I have a photo that was taken on a daylight setting under tungsten lights. I want to correct the colour but the only reference points I have are the skin tones. I have played with colour balance and curves but I can't quite get the result i am looking for. is there another way to do this? normally i would set the black, white and grey points and it would be fine but none of these shades exist in the image (an image in the background that comes from a data projector)

thanks
Simon