How do I set white balance when there’s no neutral gray or white in the photo?
Asked 3/20/2012
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If a photo contains no neutral white, gray, or black area to sample with a white balance eyedropper, what’s the best way to correct white balance? I’m especially interested in both getting close in post-processing and achieving accurate color when the lighting setup is known.
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
14y ago
2 Answers
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You can mimick auto white balance using Photoshop's Average Blur filter in a duplicate throw-away layer. This will determine the overall color cast in the image. Then add a curves adjustment layer, use the gray point eye dropper and click on your average blur layer, which will turn it to grey. In other words the curves layer will neutralize that color cast. Then remove the average blur layer, and the curves layer will make that same adjustment on your overall image.
This is basically what your auto white balance does in camera. Samples all the light coming in and adjusts.
If your image is a close up of skin (red) or a forest (green), then the light should have a red or green cast to it, so this technique may overdo the adjustment (so may your auto white balance). If so adjust the opacity of the curves adjustment. It will at least point you in the direction of removing the dominant color in the image.
So the steps again are:
duplicate your layer in Photoshop
in the top layer, Filter > Blur > Average
add a curves adjustment layer
use gray point dropper, select the color in the average blur layer
delete the average blur layer
adjust opacity of curves layer
Originally by user4191. Source · Licensed CC BY-SA 4.0
user4191
14y ago
0
Generated from our catalog & community — verify before relying on it.
If there’s no neutral area in the image, the most reliable solution is to create one: photograph a gray card (or better, a color checker) in the same lighting setup, then use that frame to set white balance for the rest of the series. You’ll need a new reference shot whenever the lighting changes.
If you don’t have a reference shot, use your editor’s white balance presets for the scene lighting (daylight, tungsten, etc.) as a starting point.
A rough fallback is to mimic auto white balance by averaging the image color cast and neutralizing it. In Photoshop, one approach is to duplicate the image, blur/average it until it becomes a single overall color, then use a curves adjustment with the gray-point eyedropper on that average color. This can work, but it may be wrong for scenes that are naturally dominated by one color, such as skin close-ups or forests, because the scene itself is not neutral.
So: for accuracy, use a gray card/color checker; for approximation, use presets or an average-color method and fine-tune by eye.
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