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Exported images darker than originals
#1
Hi,
I'm using GIMP 2.10 for astroimage processing. When I export the final image as tif or png, and reopen in Windows (7) next to the original image in GIMP, it appears significantly darker. I tried to no avail:
Reducing bit depth and switching between linear and perceptive mode.
Is this a bug or a feature? How can I save my images "as is"? Never had this problem with 2.8.
Any help would be very much appreciated!
Thanks and best regards,
Pat
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#2
I suppose it will depend on the processing done. You already checked between bit depth and perpetual(sRGB) and linear modes. Same menu is a toggle for Color Management on/off and if you look in Edit -> Preferences, Color Management is much wider than with Gimp 2.8 Can you remember how Gimp 2.8 was set up?

Another possibility is Gimp 2.10 layer modes, for 2.8 equivalence change to legacy mode.
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#3
(02-22-2019, 08:04 AM)rich2005 Wrote: I suppose it will depend on the processing done. You already checked between bit depth and perpetual(sRGB) and linear modes. Same menu is a toggle for Color Management on/off and if you look in Edit -> Preferences, Color Management is much wider than with Gimp 2.8 Can you remember how Gimp 2.8 was set up?

Another possibility is Gimp 2.10 layer modes, for 2.8 equivalence change to legacy mode.
Thanks, Rich!
I basically never changed anything in the GIMP 2.8 settings related to color space or the like. I'm really just a user with not too much understanding of color spaces and related settings. I was naive enough to assume that images should look the same when displayed on the same device, no matter which program I use. I was reading quite a bit the last days and understand now that it is not that simple.
It seems that a general advice is to stick to 32 bit float and linear mode for standard image processing (for speed and precision). Then save as 16 bit linear, but make sure the GIMP image stays at 32 bit (use undo).
In your opinion, is this a reasonable approach? Any idea how I could figure out, which color space Windows is using in their viewer? Or any other way to get my images to display consistently?
What is really not clear to me: When I was trying different bit depths and modes, I saw basically only minor changes on the image in GIMP (mostly related to the change in the dynamic range when I went down to 8 bits I suppose), but when I exported and displayed the images in the Windows Photo Viewer, I saw dramatic changes. From color patterns in the background, which I didn't see before to weird effects which I only can describe as posterization (extrem bright colors where I did not see them before). Strange enough, I did not find a setting which made Windows display the images the same way GIMP does. I also viewed them in other programs (e.g. Fitswork) and they displayed just fine there.


Are there any astrophotographers around here who could share their experiences with 2.10? Which settings are you using for color space, precision and mode?
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#4
I use linux so Windows Photo Viewer is not generally available. I can not think of a reason for a difference between Gimp 2.10 and 2.8 if everything is like-for-like.

From what I read it could be a conflicting colour profile something like this;
https://answers.microsoft.com/en-us/wind...73d3c58596

Quote:Are there any astrophotographers around here who could share their experiences with 2.10? Which settings are you using for color space, precision and mode?

Maybe not here Wink A good place to ask the question is https://discuss.pixls.us/
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