[SOLVED] Weird preview in darktable

Software darktable
1

Hello, everyone!

Last week I took these photos of a cat. It was a burst of three shots, and the first one looks very weird in DT. The other two are fine.

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DT was running on Archlinux, and this is the version:

$ darktable --version
this is darktable 4.0.0
copyright (c) 2009-2022 johannes hanika
darktable-dev@lists.darktable.org

compile options:
  bit depth is 64 bit
  normal build
  SSE2 optimized codepath enabled
  OpenMP support enabled
  OpenCL support enabled
  Lua support enabled, API version 8.0.0
  Colord support enabled
  gPhoto2 support enabled
  GraphicsMagick support enabled
  ImageMagick support disabled
  OpenEXR support enabled

My camera is a Canon 90D. SD card is kind of old, maybe a few years. But I’m not sure if it’s faulty. In google drive the raw file looks fine. It only looks weird in DT.

These are the raw files and the exported jpg: weird_colors_in_dt – Google Диск

If any other info is needed, please ask.
Thanks in advance!

2

Do you have OpenCL turned on? If yes, try disabling it.

3

I believe it’s disabled.

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s809×564 63.4 KB

4

The correct looks in other apps might be due to embedded preview jpegs?

I have two files like this wrongfully written to sd card.

1 Like
5

Opened the file in rawtherapee and I faced the same problem.
@hannoschwalm was right. The embedded preview is OK, and that’s why looks OK elsewhere.

I’m going to mark this thread as solved, since it’s a problem in the SD card probably.

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6

Oh, and thank you very much!
I just forgot that, in raw files, what one sees is not the actual data but a embedded preview.

7

Just a final comment as you shot a burst. Have you tried to do repeated burst shots and check if this could be not a single issue? Could be a firmware problem in your camera. Had such an issue too, that was a Leica and they fixed it.

Edit: could also happen if you change raw data by exiv2 or exiftool in write mode and there is a bug in that soft.

8

Once I had an SD card that didn’t work reliably in my Nikon DSLR, but always tested fine when I wrote to it using my card reader, and never had problems in my wife’s Panasonic compact camera.

1 Like
9

Yes. I shoot bursts to animals most of the times. This is the first time I see this.

If I see this with a different card, I’m going to start worrying.

10

Along similar lines, but a little different:

I also saw something similar before on a Canon DSLR way back in the day with a CF card. (This is well over a decade ago.) Some photos would become corrupted similar to this if I didn’t format the card in the camera directly.

I’ve also had filesystem corruption on both CF and SD cards before when I didn’t format it directly in the camera, but formatted it on a computer instead. (When this happened, PhotoRec saved the day!)

Formatting (in-camera) instead of erasing images from your media is good to do too.

Theoretically, it shouldn’t make a difference, but the firmware of cameras can be finicky when it comes to how the filesystem is created, and your computer might do it slightly different.

4 Likes
11

Good advice, even though it didn’t work for that specific card. I always format at card in the camera.

Interestingly, I also had random corruption with an SD card (a different one) and a Raspberry Pi. I did some research and found a very long discussion about the topic, but ended up with using the card in another device, and using a different card in the Pi. It seems there is some slack in the SD specs that can lead to rare and weird issues.

Both cases (the one with the camera and the one with the Pi) happened a long time ago.