Hi Olaf,
You may consider checking “Lighttable/Global options” first. You might have changed something there without noticing.
Or, you can open and save another photo (with similar colors, with just a basic processing) to see whether it also shows the same abnormality.
I’m not certain that it isn’t a color profile issue but I have never had any wish to change the color profile settings since everything was working fine (apparently) using all other tools. Color profiles are a hard subject to fully understand. After having experienced the problem and before posting I have studied the manual and looked through the settings without succes.
My settings are the following (pls let me know if I have left out some settings):
Your file format setting is 8 bit jpeg with a low-ish quality (73).
That may be too low to reproduce the colors you saw on darktable screen.
As an example, my settings are Tiff, 16 bit. Just a thought.
I have also tried it with JPG quality (100) and with Tiff (maybe this was 8 bit can’t remember) same result. I think that the differences are so big that there must be some other explanation.
Hi’ @bc_the-path
So you think it’s a bug?
Here is another example. Almost no editing is taking place except for haze removal (just to demonstrate the effect) and output is 16-bit TIFF. I also upload the xmp.
DSC_0609.NEF.xmp (17.0 KB)
Hallojsa!
Please check your OpenCL settings (as per post above).
If you have it On, turn it Off (and restart dt to be on the safe side), and make another test.
Mvh
Claes fra Lund, Sverige
Hej Claes, hyggeligt at høre fra dig igen………
Turning OpenCL off doesn’t make any difference.
Look at the result using RT 5.5. for haze removal below. The RT editor view and the JPG are very much like the TIFF in the latest example. So it seems to me that the darkroom view could be wrong?
Haze removal will darken and alter colours as you see in your export so maybe the display while editing is not updating correctly to diplay the effects of the filter…not sure why that would be though…
Hi’ everybody
Thank you for many responses and ideas, but no solutions or explanations have materialized.
I have installed 2.6.2 from scratch on another windows pc running only default settings. Same problem.
I will upload the photo and the xmp. I hope that some of you will test to see if the problem exists on other platforms and systems………?
DSC_9861.NEF (30.7 MB)
DSC_9861.NEF.xmp (17.6 KB)
The haze removal is taking a lot of the colours out of gamut so I’d guess that’s at the root of the problem.
Yes, I know and I have given it som thought. The blue sky is not out of gamut in the darkroom view and yet the color of the sky is changed a lot in the exported image?
Well yes, that’s the point. I was thinking that you’d expect the out of gamut colours to change as they’re moved to the output colour space. But you wouldn’t expect the dramatic changes seen in other areas of the image. I’m specifically looking at the lighter patches in the distance.
Anyway, even bringing the whole image back into gamut doesn’t solve the issue.
However, changing the basecurve (are you using nikon like alternate?) to nikon like seems to get close. View at 100%.
Hi’ @Marctwo
I get the impression that you have done a test on your own system. If so, what platform do you use and what did your test show?
When I change the base curve from “Nikon like alternate” to “Nikon like” then the preview and the exported image change like they should and the preview is now closer to the export especially when you look at the sky in 100%. The result is closer but there are still a lot of differences also in areas within gamut. Don’t you agree?
It’s essential that the preview looks as the exported image. If not, why should you spend time using editing software to fine tune your photos?
Is this a “real” problem only occurring on the windows platform and using haze removal? And what steps can be taken to properly document and fix the problem?
Let me add to @obe’s questions:
What would be a good way to spot this
problem/behaviour already in the preview
(i.e. before export)?
Some kind of soft proofing?
I’m on Win7 and yes, I’ve had a play with it. Like you, I’ve found the results wrong whatever I try (while keeping the haze removal settings). Various things get the preview closer to the export (eg. demosaic - ppg) but it still isn’t right. I’ve also found exporting jpgs and tifs gives different results.
So no, I can’t find anyway of correctly previewing/predicting the export results for this image. But I’m quite new to darktable so maybe one of the more experienced heads will come up with something.
I don’t use darktable, but GIMP’s de-haze does the same thing with color shifts. And it’s not limited to GIMP. I found the following Photoshop article that addresses this issue: A Quick Cure For Dehaze Color Shifts With Photoshop - John Paul Caponigro
Thank you for the article.
As I undertand it we must consider two different problems:
Haze removal causes color shifts but you can readily examine these color shifts in the preview. The article describes how to get around this using several layers which is not possible in DT. These color shifts are apparently inevitable using haze removal, especially if you push the sliders to max. I don’t consider this a problem…
The problem is that the export is different than the preview in areas within gamut and out of gamut. This seems to be a bug.
I don’t know if this is the case in the windows version only. So I’m hoping for feed back on this issue from non-windows users of DT.
Hello Claes
Look at this feed back:
What to do now?
Olaf fra Copenhagen, Denmark
