Here’s my edit:
_CTW2190_10.nef.xmp (19.3 KB)
Here’s a screenshot from dt:
The screenshot is what it looks like in dt. Big difference in sharpness and local contrast.
My export setup is:
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You should preview those at 100% in darkroom. Otherwise the image is scaled and it won’t be that accurate.
If I export at full size and have it printed, what size does the print have to be to match the 100% preview?
Depending on your speed settings - I think - it is the zoomed-out preview that “isn’t correct”.
Specially the diffuse and sharpen module is noticeable I think , in producing different results depending on the resolution being rendered.
I think you can modify the preview settings to not run it at half res or something to be more accurate to your 100% result.
A different method, although I call it reverse thinking, there are no bad methods just results:) - is to turn OFF 'high quality resampling ’ in your export settings.
If you have it ON, it means render the whole image at original resolution, then resize afterwards.
If you have it off , it means ‘render the image at the specified output resolution’.
Since your screenshot is 1874px long side, you can export at 1874 x 1874 with high-quality-resampling off. You will get an image looking just like your preview. Resize it down further if you want to in any image tool.
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If I export at full size and have 'high quality resampling’ on or off doesn’t appear to make a difference. If I have it off and export at a lower resolution, it appears to be closer to what I see in the preview.
I think the fundamental issue is that I am editing without seeing what the actual image is. Zooming to 100% can tell you what a small area looks like, but the only way to see what you are accomplishing with the whole image is to periodically export full size images and check those out.
I did change the preview resolution to 1/2, and that did make the preview look more like what I remembered the 100% zoom at full resolution looked like, but if I want to zoom to 100% while I’m editing at 1/2 resolution, won’t that give me a false perception then?
Is there a way to have two previews, one at 1/2 resolution and one at full?
No, because it only affects things when exporting to a smaller resolution than the native one of the file.
Yes, but in this is kinda what is ‘the most true’.
Your only correct preview is the 100% zoom preview. Other tools like DxO and Rawtherapee have something similar, where only certain modules become active at certain zoom levels, etc…
The problem comes from the preview - zoomed out to fit - is a 1874px-wide image in your case (give or take 
). So if Darktable runs its pipeline at 1874px wide, some modules behave different compared to when being fed the entire 50mp input file (or whatever you use).
To get previews quicker, Darktable renders the preview at the number of pixels that are actually on screen at that time. And when you export to full size (or with high-quality-resampling enabled) the pipeline renders at the full native resolution of your input file, which is probably a lot bigger than your ‘fit’ preview window.
So, if you preview-to-fit, and that is around 1800px at the long end, exporting to 1800px at the long end with high-quality-resampling TURNED OFF will result in exactly the same as you were seeing in the preview.
But if you export at a higher resolution (or lower), it will change again.
That’s why normally you keep high-quality-resampling enabled and then use the 100% view to judge how the image will look. And yes, you will have to check that occasionally.
Like I said, this happens mostly with diffuse&sharpen I believe. A lot of the other tools are not affected. Most people don’t seem to be bothered by this. I at least use 100% to judge anything related to ‘details’, and zoom out to judge things like exposure / color / tone-mapping. In every photo tool.
To be sure, in the settings in the section ‘darkroom’, there is an option just above the ‘modules’ header that is named ‘reduce resolution of preview image’. Is that still set to ‘original’ in your case?
If some other guru out there knows if there is a setting - and if so, which - to make sure your previews are always rendered at full input-file resolution, then that will be a solution for you. But it will make things (much) slower.
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I tried 1/2, 1/3, and 1/4. I have to try it out some more to decide what works best.
You have given me much to work with. The final test is to have something printed and see how it compares to various views onscreen.
Thanks.
that setting just affect the preview image (as shown in the preview panel) not the main area. but this preview is used for calculation of module settings (e.g. color picker, masking, …)
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