Can you adjust white balance in a digital image using Photoshop (or similar) in such a way that average blurring the entire image gives gray (R=G=B)? Note, I'm not necessarily looking to achieve "correct" color balance with this method.
Can you adjust white balance in a digital image... in such a way that average blurring the entire image gives gray (R=G=B)?
But why would you want to do that? It's easier to desaturate.
The following image made by adjusting colors and curves, not by decreasing saturation.
Can you adjust white balance in Photoshop based on average blur?
It's a useful technique to try with difficult images, but results likely won't be what you're after.
... a typical scene when projected and diffused will produce gray if correctly balanced.
Anyone who has seen diffuse colored light reflected from a projector screen has seen a demonstration that this isn't true.