Color Cast - Easy Removal

[DigitalScape]

I ran across this method of dealing with pictures that have a slight color cast. The following method was "authored" by Charles Glatzer.

1. Duplicate the background layer
2. Select the duplicate background layer
3. Filter > Blur > Average (this produces a solid color matching the color cast)
4. Open Levels Adjustment Layer, click duplicate background layer image with the middle (gray set) eyedropper.
5. Deselect layer visibility icon (eyeball) of duplicate background layer
6. Tweak the adjustment levels layer opacity to suit taste (~50% is normal)

I followed this methodolog on a following photo:

Before (i.e. with color cast)


After (removing the color cast)

[ThePhilosopher]

That's a neat trick.

[Duffy Pratt]

As I read it, this trick will only work when the "average" color is a neutral. You could easily have a scene that is heavily biased to one color, and yet still has a cast. This approach would do more to kill the natural color bias than the cast. (For example suppose you had a scene that was a person in the foreground against a very blue sky. The skin tones could be way too yellow, because indicating a yellow cast, but the blue sky (which is not blue enough) would dominate. Use this method, and you should pull blue out of the sky, and make the yellow skin even more yellow.

That said, if you understand what this method is doing, there are times when its worth a try.

If you want, I'd be curious to see some examples of this technique where there are more or less known colors involved: skin tones, stop signs, traffic lights, whatever....

Duffy

[Duffy Pratt]

OK, I decided my last request wasn't fair. So I did a quick example to show what I'm talking about. The picture is of my dog papa (who is almost pure white) against a grass background. The dominant color in this scene is a sort of dullish green in the grass. It's offset some by Papa's tongue. Still, my guess would be that applying the technique to this picture would make Papa's fur tend toward magenta, and would make the grass turn dull. Here are the results. See how much more magenta his fur is in the second example. The technique actually added a cast to this picture.

So, as I said before, if you have good reason to believe that the average color of your scene should be close to neutral, then use this technique. Or just try it to see if you like it. It only takes a second. But don't imagine that it will work on everything.

Duffy

[xseption]

Thanks for sharing!

~ edd

[DigitalScape]

Duffy,
Thanks for pointing out an issue for using this methodology as general use. You raised a very good point (your example does show the problem).