Difference between preview and exported picture

There is difference between photo in preview window in Darktabe and exported picture:

Preview Pic in Darktable:

Exported picture (preview from Gimp)

Preview picture in Darktable looks much sharper.
I’m noticing this after using noise reduction and high pass filter in Darktable.
I’m using Darktable 2.2.4 but I had same issue with older versions too.

What I’m doing wrong?

Here is original file:_DSC7839.NEF (25,7 MB)

and _DSC7839.NEF.xmp (2,6 KB) file



I’m not sure I understand “(preview from Gimp)” for the second picture. There is two possible previews, the one embedded in the RAW or the one rendered by darktable from the pixelpipe. Maybe that’s the issue?

No. Second preview is from darktable exported, processed tiff opened in GIMP for further editing.

So, preview rendered by darktable in the darkroom mode differs from exported rendering result. Darkroom preview is much sharper as end result. By the way, rendered result looks same in every other viewer, so this is not GIMP issue.

Do you export in full resolution or limit the image dimensions in the export modul?

If your limit the image dimensions, what is your setting in the core options for “do high quality resampling during export”?

@pk5dark Yes I export in full resolution:

This option is on.

Ah, sorry I just checked your sample image now. The reason is the “profiled denoise” modul and the way how the image preview is generated. To make it fast the preview only takes “part” of the image. IRC in the full image view, the image is not even demosaic? Once you zoom in a bit you will notice, that it gets unsharp like the export.

To tweak the denoising I always use the 100% view. The default settings of profiled denoise are too “strong” most of the time. So you need to change the values. I use the approach described in the manual with the two different modes and blending. And for demosaicing I switch to “VNG”.

@pk5dark thanks for taking time, testing and response but even after your suggestions (applying demosaic and tweak denoise with blending modes described on manual with 100% view) I don’t see any changes. On the left side is preview in darktable, on the right exported tiff:

My problem is that I had a nice job to document an event but there was bad lighting and I could not use flash to not disturb the performance, so I was forced to use higher ISO values. Now I have about 200 photos and lot of them need to be edited and noise suppression makes me headache.

Well I’m not an expert in this. Here is my quick and dirty first try: _DSC7839.NEF.xmp (2.9 KB)

There is something more. If you use OpenCL there was a bug, which resulted in differences between CPU and GPU profile denoising: https://redmine.darktable.org/issues/11481

Ok. Thx a lot for your help pk5dark!