(Thanks to deadpixel for teaching me how to do a ab swap)


1. Auto-levels
2. convert to lab colours
3. open up curves
4. Under channel a, change the curve so that it is sloping downwards instead of upwards
(IMG:http://img100.imageshack.us/img100/6764/abswapqq6.gif)
5. Under channel b, change the curve so that it is sloping downwards instead of upwards
6. convert back to sRGB

you can do your usual processing before or after the swap