Automatic levels: knowing the equivalent parameters changes

Ideas for improvements and requests for new features in XnView Classic

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Symoon
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Joined: Sun Aug 02, 2009 10:32 am

Automatic levels: knowing the equivalent parameters changes

Post by Symoon »

Hi Pierre,

I'm scanning negative films, and using the great XnView Classic to set better colors. Scanned negatives usually have borders that cover a larger picture taken on the negative film (see picture below, outlined in green you can see the whole picture, though there would have been better examples I confess! ).
As I don't want to lose a single bit of the pictures taken, I wish to include those white parts on the final savec picture.

Problem: those large white borders mess with the Automatic Levels command, the result is really better... Without them ! So I would like to apply the automatic correction based on the central image (without the white parts), to the WHOLE picture.
In order to do so, would it be possible to know, in a way or another, the settings (color balance, brightness or whatever) applied by the Automatic Levels command, so I can re-create the ones made on the small picture without borders, to the larger one with white borders?
(it would also allow me to use the same setting to other pictures on the same negative film, because usually the same corrections work fine).

I suppose it might not be so easy to "translate" the automatic levels modifications to user-based commands...
Anyway, just an idea ;)

Cheers
Simon
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xnview
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Re: Automatic levels: knowing the equivalent parameters changes

Post by xnview »

it's based on histogram of image, so not the same for every picture
Pierre.
Symoon
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Joined: Sun Aug 02, 2009 10:32 am

Re: Automatic levels: knowing the equivalent parameters changes

Post by Symoon »

xnview wrote: Tue Aug 03, 2021 2:25 pm it's based on histogram of image, so not the same for every picture
That's my point exactly. Example:

1. scanned negative film:
Exemple2_negatif1.jpg
2. Automatic levels from the cropped picture (great colors):
Exemple2_negatif2.jpg
3. If I don't crop, as the histogram is different, the automatic levels give another result (obviously it was better in picture 2) :
Exemple2_negatif3.jpg
So I would like to be able to apply the levels changes made on picture 2, but to the 1st picture (I want to have the great colors, AND the full borders).
Do you think there's any possibility to achieve this? A sort of "repeat levels modification"?
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xnview
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Re: Automatic levels: knowing the equivalent parameters changes

Post by xnview »

so for example select an area (rectangle) and apply to full image?
Pierre.
Symoon
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Re: Automatic levels: knowing the equivalent parameters changes

Post by Symoon »

xnview wrote: Wed Aug 04, 2021 7:52 am so for example select an area (rectangle) and apply to full image?
Yes, that could be another way to do it! :)
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xnview
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Re: Automatic levels: knowing the equivalent parameters changes

Post by xnview »

i've checked, and it works already like that when selecting a rectangle
Pierre.
Symoon
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Joined: Sun Aug 02, 2009 10:32 am

Re: Automatic levels: knowing the equivalent parameters changes

Post by Symoon »

xnview wrote: Thu Sep 02, 2021 2:56 pm i've checked, and it works already like that when selecting a rectangle
Thanks for having checked. That's strange, I tried with the latest Classic version (2.50.1), and it selects the colors from the selected rectangle, but only applies changes to the selected rectangle (which is fine), not to the full image (which I would enjoy an option for ;) ).
Symoon
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Joined: Sun Aug 02, 2009 10:32 am

Re: Automatic levels: knowing the equivalent parameters changes

Post by Symoon »

Ok, as I still don't understand your reply, I have done some tests to try and clarify, with both XnView calssic and XnView-MP (0.83, as I'm working with Windows XP).

It appreas that both Classic and MP seem to work the same way.
When selecting a rectangle:
- the colors are taken from the whole picture
- the change is applied to the selected area

What I was talking about in my post from "mar. août 03, 2021 4:25 pm", would be an option, to do the opposite:
1- the colors are taken from the selected area
2- the change is applied to the whole picture
Exactly what you said in "so for example select an area (rectangle) and apply to full image?" ;)
But it's not working like this today, or at least I don't know how to do?