Bug #10078

DNG ver 1.1 & 1.3 images bad pixels not corrected

Added by Denis Robbie almost 5 years ago. Updated about 2 years ago.

Target version:
Start date:
Due date:
% Done:


Affected Version:
hardware architecture:


I chatted with houz and parafin on IRC and they recommended I submit a bug report.

Darktable does not appear to handle bad pixels correctly in DNG files. Bad pixels appear to be displayed as black and are not corrected. PS CS6, CC, and Lightroom correct these DNG images perfectly. Dark Therapee also handles the bad pixels properly. Darktable seems to ignore them and display them as black.

Also same problem with ver 1.5+1760

Images were created with a Canon G9 and in camera DNG files with CHDK. It is very hard to see any bad pixels in the Canon Raw file. My sensor had a very low count only 930 (must be some statistical method to determine out spec pixels). Black pixel problem compounds when combining images for HDR.

sample files are located at

Thanks guys you have created a great editor.



<denis_> Hi ... is anyone available to discuss darktable DNG support?
<LebedevRI> anything specific?
<denis_> I am using a Canon G9 with CHDK. Just recently started using the in camera conversion to DNG. Darktable 1.4.2 and the recent development does not display the images correctly
<LebedevRI> git master should be able to open those
<parafin> those aren't DNG I think
<LebedevRI> denis_: if you are sure that it is still not supported by DT, provide sample
<denis_> My camera has roughly 900 bad pixels .... they are appearing as black pixels in the image. If I use PS LR or Raw Therapee images are displayed properly with the bad pixels corrected. I am using darktable in Linux Mint 16 & 17.
<denis_> It appears to be a problem with a lot of the other Linux editors ... both DNG ver 1.1 & 1.3
<denis_> I can send some image files that illustrate the problem
<parafin> so it renders image correctly, just don't correct bad pixels?
<denis_> yes
<denis_> exactly
<houz> are those marked as being bad in the dng?
<parafin> sounds more like feature request and not a bug. I wonder if hot pixels module can correct dead pixels too...
<denis_> I assume they are as PS Lightroom, CC and CS6 doesn't display them
<denis_> Raw Therapee seems to handle them the same way as PS
<LebedevRI> parafin: i only see hot pixel (if (*in > threshold) ...) fixing in hotpixels iop
<denis_> well it is not normally a big deal but if you combine images for HDR that you have aligned the bad pixels get multiple if the images are slightly deregistered
<denis_> I can send some example files of the native raw CR2, DNG ver 1.1 and DNG ver 1.3 files (shots of a white card)
<denis_> I think this may be a problem of the raw converters ... LuminanceHDR also has a problem with them ... even Photomatix under windows
<houz> could you upload a sample somewhere?
<houz> and put the link in a bug report on redmine
<houz> !newbug
<denis_> ok will do ... I'll put the files on my dropbox account
<parafin> do we have any code that corrects dead pixels? maybe in rawspeed?
<houz> i don't think so
<parafin> dcraw for example has such functionality AFAIK
<houz> denis_: and maybe put an example from raw therapee in it, too. so we can see what the result is supposed to look like
<LebedevRI> new deadpixels iop could be added, but it will fix all detected dead pixels, not only those that are marked as dead somewhere in metadata
<denis_> ok ... I'll put the files there in a few hours ... it is lunch time here ... central canada
<denis_> thanks

Associated revisions

Revision 0a3da2c1
Added by Roman Lebedev over 2 years ago

Rawspeed submodule update. Dng fixes. Dead pixel fixes.

Fixes #10078.


#1 Updated by Pedro Côrte-Real over 3 years ago

  • Status changed from New to Fixed
  • % Done changed from 0 to 100

This should be fixed in current versions of darktable as rawspeed does bad pixel interpolation for DNGs. Thanks for the report.

#2 Updated by Joe Giampaoli over 3 years ago

Pedro Côrte-Real wrote:

This should be fixed in current versions of darktable as rawspeed does bad pixel interpolation for DNGs. Thanks for the report.

This would be great! I have the same issue with DNG's 1.3 created by CHDK I am forced to use DNG 1.1 with their automated "badpixel.bin" file, but it requires more camera memory to map out those black pixels during shooting and would be nice to see it fixed better in post.


EDIT: I see this is marked as 100% fixed, I am currently using DT 2-RC3, is this already implemented?

#3 Updated by Roman Lebedev over 2 years ago

  • Status changed from Fixed to Incomplete
  • % Done changed from 100 to 20

#4 Updated by Roman Lebedev over 2 years ago

  • Status changed from Incomplete to Fixed
  • % Done changed from 20 to 100

#5 Updated by Roman Lebedev about 2 years ago

  • Target version set to 2.4.0

Also available in: Atom PDF