Purple flare: Causes and remedies

Started Mar 1, 2013 | Discussions thread
OP Anders W Forum Pro • Posts: 21,468
Re: Hmmm... CC experiment implies non-linear process...

kenw wrote:

Thanks for sharing this Anders.

The polarizer does strongly imply reflection. Keep in mind though the AA filter depends on polarization as well, and your most recent experiment showing the horizontal and vertical flares implies something not rotationally symmetric and aligned with the AA filter and pixel array is at least partially at play. Would be curious to see a polarizer test with a diagonal purple flare to narrow down the likely causes...

I'll see what I can do about creating a diagonal purple flare and attack it with the polarizer.

The bigger question to me is the CC filter result. It implies a non-linear (i.e. violating superposition) process is occurring. Such things are exceedingly rare in optics as superposition is a basic tenant of E&M theory. Immediately attention is drawn to the sensor itself or the post processing (recovering WB and exposure compensation) as the only likely sources of a non-linearity. Do you have a theory for what is going on with the CC filter experiment?

Yes I do have a theory. See here. It is nonlinear all right, but not, I think, in a manner that violates the superposition tenets of E&M theory.

Now I am curious to hear what you think of the theory and the evidence I have so far managed to produce in support of it. If you can kill it, that's fine. As usual, that means we have learnt something anyway. If you can't kill it, that's even better of course.

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