I used a technique for removing a color cast, where I find three parts of the image that are white (paw, floor, shadow on floor) that have different amounts of light. White should be equal red, green and blue, so I raised the blue and lowered the red to match the green on each spot using a curve.
|Here's the original RAW file (as JPEG but with no cleanup)|
|My fix (using GIMP, normalizing RGB on three points)...|
Olympus wins this round. I think it cheated, but I can learn from cheaters.
Full credit to the lesson I found at Grokking the GIMP