So I noticed this problem recently with darktable 3.0.1 in my computer.
Does anybody know how to fix this?
You can see the issue in this screenshot. Low light region is rendered in a strange way in darktable. It’s totally crushed. It’s fine in other raw developer and image viewer though.
What I have tried:
Thank you!
Hmmm, weird. But I can not confirm. Using dt 3.1.0+1141 I get a smooth transition from black to white in the lower part of the image, and the steps are clearly resolved in the upper part, as expected. What OS are you using ? Color Management System ?
My histogram looks different :
The history module was not opened when you took the screenshot, so one can not see which modules you applied. In my case the default settings after import are used :
Hi,
I will try to provide more info. This one is really weird for me because I don’t have that problem in my other Linux and OSX machine.
This third one is a Linux laptop. I use colord for color management.
$ darktable --version
this is darktable 3.0.1
copyright (c) 2009-2020 johannes hanika
darktable-dev@lists.darktable.orgcompile options:
bit depth is 64 bit
normal build
SSE2 optimized codepath enabled
OpenMP support enabled
OpenCL support enabled
Lua support enabled, API version 5.0.2
Colord support enabled
gPhoto2 support enabled
GraphicsMagick support enabled
OpenEXR support enabled
I took another screenshot so that history and module orders are visible.
The greyscale image in the screenshot is taken from here Of Histograms and Waveforms | darktable
Just moved to an other machine where 3.0.1 is installed. It’s an older hardware, no color management, just a mostly original Ubuntu 18.04. Did a fresh import of the sample image you linked. Module order and history are the same as shown in your second sreenshot. Tried with different input color profiles. I’m not able to reproduce the behaviour you describe. Everything looks ok here, image shown in the image area and corresponding histogram.
Try turning off OpenCL …
I see the same. No problem on darktable 3.0.1 on Kubuntu 19.10, NVidia proprietary drivers and colord enabled.
Have you tried disabling color management at the OS level (or changing the color profile there)? Maybe the problem is with the monitor profile.
@pehar @guille2306 I tried with color management disabled/enabled, it still shows same weird thing. I also tried current git version and same issue.
With raw images, it also exhibits same behavior.
As I said in the beginning, I don’t notice the same issue in other applications.
@asn I’m using Intel GPU and didn’t install opencl support libraries for it so … I even checked in darktable settings and the setting about opencl is grayed out.
What is your working space ICC profile set to?
dt comes with the tool darktable-cmstest ( see https://www.darktable.org/usermanual/en/color_management.html ). Possibly you may want to check what information you get using this utility. Are there warnings for incorrect settings ? And you can compare it’s output with the settings of your other machines not showing the issue. It is extremly difficult to give expedient hints because obviously no one is able to reproduce the issue you describe.
Ok, thank you for helping!
Another consideration (maybe far-fetched, but I had such a case years ago on Windows) : Is it possible that you accidentially added a color profile to the metadata of your testfile grey.png ? For comparison I copy the output of exiftool for the “original” file :
[ExifTool] - ExifTool Version Number : 11.93
[File] - File Name : grey.png
[File] - Directory : .
[File] - File Size : 88 kB
[File] - File Modification Date/Time : 2020:04:10 07:51:27+02:00
[File] - File Access Date/Time : 2020:04:11 15:47:30+02:00
[File] - File Inode Change Date/Time : 2020:04:10 07:51:27+02:00
[File] - File Permissions : rw-rw-r--
[File] - File Type : PNG
[File] - File Type Extension : png
[File] - MIME Type : image/pngv
[PNG] 0x0000 Image Width : 638
[PNG] 0x0004 Image Height : 400
[PNG] 0x0008 Bit Depth : 8
[PNG] 0x0009 Color Type : RGB with Alpha
[PNG] 0x000a Compression : Deflate/Inflate
[PNG] 0x000b Filter : Adaptive
[PNG] 0x000c Interlace : Noninterlaced
[PNG] - Background Color : 255 255 255
[PNG] 0x0000 Pixels Per Unit X : 2835
[PNG] 0x0004 Pixels Per Unit Y : 2835
[PNG] 0x0008 Pixel Units : meters
[PNG] - Modify Date : 2013:03:29 16:50:47
[PNG] - Comment : Created with GIMP
[Composite] - Image Size : 638x400
[Composite] - Megapixels : 0.255
You get this output (prerequisite exiftool installed) as a file grey.exif using the command
> exiftool -H -G -a -w! .exif grey.png
No, it happens to any image. Not just the grey one. I showed that one because it’s easier to see the problem.
@pehar I am puzzled. What if we try to circumvent the problem… … what kind of setting(s) might produce such a result?
Faulty black level correction setting?
Have fun!
Claes in Lund, Sweden
I am confused, too. Circumventing the problem may be a workaround but not a real solution, it does not touch the root of the problem. My suggestion leads me in the direction of a faulty system setup of the color management. As baongoc124 says : “it happens to any image”.
Please look at the first screenshot of the initial post. The exposure module is opened and shows the default settings, in particular black level correction is set to 0.000.
Only to make sure : did you check the file(s) metadata with exiftool ? Are there embedded ICC profiles ? And did you use the tool darktable-cmstest ? With what result ?
Edit : And, of course, you could try to go a more pragmatic way and try starting dt with virgin parameter settings. To do so :
~/.config/darktable with all its content (settings, databases, styles …) on a safe placedarktable from ~/.config/grey.png is in original state (not modified by any other application)grey.png.xmp alongside the image file/path/to/darktable /path/to/grey.pngdarktable in ~/.config/ with new libraries and settings and show the image in darkroom, issue still present ?Use man darktable to show the manual page of dt, there are several commandline options you can use at start of the program (debugging, setting config directory …)
Hi, a little update! I turned to other apps for a while and tried random things, and my darktable is back to normal. So now I’m happy. But I cannot pinpoint why it happens so that also bothers me. Maybe because recently I updated xiccd in my computer… But I’m not sure.
Thank you guys for helping!