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Histogram of all visible layers

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Histogram of all visible layers
Feliks Offline
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#1
08-02-2024, 03:26 PM
Is it possible to see a histogram of all visible layers combined (and not only of the active layer). I want to tweak different layers and see what it does to the final result. If that is not possible, is there maybe a plugin that can do this ?
Thanks.
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Ofnuts Offline
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#2
08-02-2024, 09:41 PM
Not AFAIK and it is indeed a great miss. AFAIK best you can do is Layer > New from visible and check the histogram of that. But I would he very happy to learn otherwise...
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Tas_mania Offline
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#3
08-02-2024, 10:04 PM
"A histogram is a visual representation of the distribution of quantitative data".

If your layers have an alpha channel you can manually make the higher ones transparent to see layers below. If you merge down, then the transparency position is retained in the layer stack.

BTW don't know why this would be used.
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Ofnuts Offline
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#4
08-03-2024, 08:03 AM
(08-02-2024, 10:04 PM)Tas_mania Wrote: BTW don't know why this would be used.

My most frequent use case is checking the difference between two layers. I put one over the other with the top in Difference mode. The more equal the image, the darker it is. But if you want to see the effect of something subtle like JPEG compression you need the histogram of the difference, and currently I have to do a Layer > New from visible just for this.
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Tas_mania Offline
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#5
08-03-2024, 10:01 PM
Quote:My most frequent use case is checking the difference between two layers.

You reminded me of a great use for histograms - mapping. I made lots of maps like geology maps this way. Now I do most online but when I go out with my detector I need to know land ownership, historic activity and current landmarks.
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Feliks Offline
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#6
08-05-2024, 12:57 PM
(08-03-2024, 08:03 AM)Ofnuts Wrote:
(08-02-2024, 10:04 PM)Tas_mania Wrote: BTW don't know why this would be used.

My most frequent use case is checking the difference between two layers. I put one over the other with the top in Difference mode. The more equal the image, the darker it is. But if you want to see the effect of something subtle like JPEG compression you need the histogram of the difference, and currently I have to do a Layer > New from visible just for this.

Yes, this is exactly what lead to my question as I was aligning lots of similar layers! Now I had to 'New from visible' and look at the histogram of that, which is very time consuming. Maybe I'll have a look at scripting. Thanks for the replies.
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