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Question:

Is there an algorithm that does (what I would call) "localized" gamma correction?

That is, applying different gamma corrections on different parts of an image, using a masking filter or something along those lines.

I have two images that seem to be correlated by a mix of exposure and gamma corrections, but not equally on the whole image:

First image

enter image description here

Second image

enter image description here

For further details on how these images were created, please refer to this (unanswered) earlier post.

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  • $\begingroup$ Gamma Correction is Pixel Wise operation So what stopping you from doing it easily? $\endgroup$ – Royi Aug 23 at 10:49
  • $\begingroup$ I did not mention it in this post, but the images are noisy. Although, I can generate them at any resolution. So, I have a collection of noisy first and second images, and I am trying to figure out what is the transformation from the first to the second image. $\endgroup$ – phil5 Aug 23 at 15:12
  • $\begingroup$ Also, the second image is generated (rendered) at half the lighting intensity of the first image. The solution has to hold for all intensities... $\endgroup$ – phil5 Aug 23 at 15:15
  • $\begingroup$ Could you share few images in full resolution? $\endgroup$ – Royi Aug 27 at 11:02
  • $\begingroup$ Update: the "local gamma" approach seems to work. I rendered images at various lighting intensities and fitted a gamma curve for each pixel. The family of curves that gamma correction provides seems like a good model, especially for a single stored value. To filter out some noise, I rendered at a higher resolution (supersampled?) and scaled down. I also clipped the negative (HDR) and very small values to zero and locked the gamma to 1 (linear) for those pixels. $\endgroup$ – phil5 Aug 28 at 6:25
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Gamma Correction is Pixel Wise operation.
Hence what you can do is estimate it per pixel and then average it per local area.

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