Hi everyone,
I’m using darktable 5.4.1 on Windows 11 with an OM System OM-5 Mark II (firmware 1.002) and I’m experiencing a bug where some ORF raw files open completely black in the darkroom.
Symptoms:
- The lighttable shows the embedded JPEG preview correctly
- Opening in darkroom shows a completely black image
- In the “raw black/white point” module, the white point is read as 0 (should be ~16384)
- Manually setting the white point to 16384 restores the image correctly
What’s strange: not all files from the same shooting session are affected. Files shot seconds apart with the same settings can behave differently. ISO and other settings do not seem to be the determining factor.
Comparison of two consecutive files (same camera, same day, same lens):
| P5090925.ORF (broken) | P5090926.ORF (working) | |
|---|---|---|
| File size | 22 MB | 19 MB |
| ISO | 5000 | 1000 |
| Shutter | 1/3000 | 1/180 |
| Black Level 2 | 252 254 254 252 | 256 257 257 256 |
| Strip Byte Counts | 19981555 | 17630442 |
The broken files are larger and have slightly lower black level values. Both have Sensor Calibration : 4095 290 and Valid Bits : 12 0.
Camera Model Name in EXIF: OM-5MarkII
Make: OM Digital Solutions
This suggests rawspeed is not correctly parsing the white point for this specific model, possibly related to the Sensor Calibration tag or variable compression producing different file sizes.
Workaround: create an auto-applied preset in the “raw black/white point” module with white point = 16384, filtered by model OM-5MarkII.
I can provide sample raw files if needed for debugging. Happy to upload to raw.pixls.us if that helps.
Thanks!