Bug 502052

Summary:	Not detecting rotated (on an angle) face
Product:	[Applications] digikam	Reporter:	Craig <craigfryer.au>
Component:	Faces-Detection	Assignee:	Digikam Developers <digikam-bugs-null>
Status:	REPORTED ---
Severity:	minor	CC:	caulier.gilles, michael_miller
Priority:	NOR
Version First Reported In:	8.6.0
Target Milestone:	---
Platform:	Microsoft Windows
OS:	Microsoft Windows
Latest Commit:		Version Fixed/Implemented In:
Sentry Crash Report:

Description Craig 2025-03-27 02:48:18 UTC

SUMMARY
Not detecting a face rotated about 60 degrees for the frame of the picture.
The face detection has improved greatly over version 8.5 & 8.6. Thank you.

STEPS TO REPRODUCE
1.  I had a series of photograph where there were two faces appearing with one roughly aligned as normal and the other rotated about 60 degrees from the other. The normally aligned face had no problem being detected. However the rotated on was not detected. I had face detection set to medium size and Accuracy set to 7.
2. I then progressively lowered the Accuracy to 5, then 3 then 1. In none of these cases was the rotated face recognised.
3. I then increased the face size to Large, but the rotated face was still not recognised.
4. I then cropped the image to include only the rotated face, but rotated. The face was not recognised. Size Medium. Accuracy: 7.
5. I then rotated the face to be aligned normally and the face was recognised as expected.

EXPECTED RESULT
I have seen many times before where Digikam has recognised rotated faces, so I just thought this was unusual and should be brought to your attention. Unfortunately the image contains people that don't want their image shared publicly. I could probably share the image with just a developer directly.

SOFTWARE/OS VERSIONS
Windows: 10

ADDITIONAL INFORMATION
This isn't a critical problem and it may be solved through future updates.

Comment 1 caulier.gilles 2025-03-28 05:15:16 UTC

Your sentences are ambiguous in your report. Title said "detection", and explaination uses "recognitions". Both are 2 separated process in digiKam.

Which one is affected by this regression ?

Comment 2 Michael Miller 2025-03-28 12:12:08 UTC

Hi Craig,
Please let me know if I understand this correctly.

When the face is rotated in the image the face engine isn't detecting the face in the image.  When you crop the face into its own image and then rotate the cropped image, then digiKam is detecting the face in the image.

Is that correct?

Cheers,
Mike

Comment 3 Craig 2025-03-28 22:22:35 UTC

(In reply to Michael Miller from comment #2)
> Hi Craig,
> Please let me know if I understand this correctly.
> 
> When the face is rotated in the image the face engine isn't detecting the
> face in the image.  When you crop the face into its own image and then
> rotate the cropped image, then digiKam is detecting the face in the image.
> 
> Is that correct?
> 
> Cheers,
> Mike

Yes. Apologies for misusing the "recognising" term. I should have used "detected".

Comment 4 Michael Miller 2025-03-29 10:50:56 UTC

> Yes. Apologies for misusing the "recognising" term. I should have used
> "detected".

Hi Craig,
Can you send me a copy of the image?  My email can be found here:

https://invent.kde.org/graphics/digikam/-/blob/master/AUTHORS

Cheers,
Mike

Comment 5 caulier.gilles 2025-04-11 18:13:45 UTC

Hi,

The 8.7.0 pre-release Windows installer from today have been rebuilt from
scratch with Qt 6.8.3, KDE 6.12, OpenCV 4.11 + CUDA support, Exiv2 0.28.5, ExifTool 13.27, ffmpeg 7, all image codecs updated to last version (jxl, avif, heif, aom, etc.).

Please try with this version to see if your problem still reproducible...

https://files.kde.org/digikam/

Thanks in advance
Best regards

Gilles Caulier