Well scaling is not the culprit. Here’s the file exported at 1 scaling. Still looks washed out and lacking in detail compared to the preview.
I think I get it now, what you are talking about.
Probably that intermission with the two details got me distracted.
Can you show us a screenshot of your export settings?
OP seems to be using a Mac —
didn’t we have a somewhat similar
McDiff question some days ago…?
Here are my export settings. Thanks for taking the pains to go through this with me. Also relieved to know that I dont need new glasses 
I am new here. Please point me to the relevant question.
I know, Ankur 
It was this thread I was thinking about: Colour and exp discr; Mac: diff jpg and RT view -- why? [Solved]
Have fun!
Claes in Lund, Sweden
I see that you selected the export profile as sRGB. What is your Output Color Profile set to ?
Here’s the output color profile. As far as I can tell, they are consistent.
Hi @Claes, this thread is about RawTherapee. I am using Darktable. And it seems like it was solved by an update to RT.
Correct — but irrespective of dt or RT,
color management in a Mac does not
behave like in non-Macs, which just might
be the culprit here…
For instance, what is your display profile set to?
@Claes I think the problem is not CM. Look at the first two screen shots.
There is clearly some sharpening (USM or other) that is not getting exported.
I was hoping for a style set in export, but alas, no luck.
Currently no further idea what is going on.
@kulkarniankur is this happening to all your images or just this one?
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This is happening in other images too. I have a bird whose detail I am trying to bring out, but it looks washed out and lacking in brightness or sharpness. I suspect something is going wrong with sharpening or brightening or local contrast applied to the masked area.
This is a difficult story involving a lot of image-processing maths.
- You simply have algorithms that rely on pixel-per-pixel data like blurring or sharpening. You must expect output data to be depending on scale. In modules like D&S we try to minimize that effect but it can’t be removed completely. That’s life (or that’s maths)
- If you scale at some point, you always must take some scaling maths into account. (Read about nyquist for example.) If you look into the feathers structure you will run into problems very fast. Also read about “moire” here.
- Some scaling algo are more prone to “overshoot” (lanc variants are one example)
- If you talk about preview, i guess you mean the thumbs in lighttable view or the top-left pre/overview? If you want to see what you will have while exporting (leaving out jpeg compression artefacts again) you have to zoom-in to 100% to avoid any scaling differences.
Just some additional points to think about leaving color maths out of discussion here.
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Just for clarity –
a) I did scale by 1, and the problem continues to remain.
b) By preview, I don’t refer to the top-left in darkroom, but the main central one.
As @grubernd said, there is some sharpening that is just not getting exported.
Just a thought, should I be looking at gamut clipping and enabling/disabling something?
If it is not a hassle to you could you provide an original file with its xmp file where you can clearly reproduce the problem? I am really curious as to what is going on here.
The xmp is in my first post here, as is the exported file: Masked portions different in preview and export
My original file is attached. Note: I am shooting in jpg.
Thanks for trying!
Thank you very much!
But I would really need the original xmp that goes with the file, because otherwise we are trying to fix the cause before the reason has happened. 
This file here:
does not contain any edits.
kofa@eagle:~$ grep operation /tmp/P1030322_edited.jpg.xmp
darktable:operation="colorin"
darktable:operation="colorout"
darktable:operation="gamma"
darktable:operation="flip"
When loaded into darktable:
Interestingly, the settings of the input color profile are:
But if I switch between 0 original and 1 input color profile, the image changes drastically:
embedded is not an option in the drop-down, though:
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Sorry, my mistake. I attached the wrong xmp. I believe this is the right one @grubernd @kofa
P1030321.JPG.xmp (36.3 KB)
Well, output is exactly as shown in darktable … if checked at 100%.
The rest is preview scaling.
Given the nature of this file this is not really a surprise - just as @hannoschwalm has said, Math is brutal. It does exactly what it is supposed to do. And with noise and JPG artefacts all over the place the outcome at different zoom levels can be quite different.
Sorry, there is nothing we can do. 
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