[digiKam-users] How to actually use Face Accuracy?

[Thomas D]

Hi,

I am having difficulties understanding how to use the  Face Accuracy
options in the  Settings for face  detection.

This is a screenshot of how the Settings tab looks like:

[image: image.png]

Here we have a progressbar (note: maybe this would be better as a  slider)
showing some percentage. By default it is 70 %.
I suppose this means that found faces are matched if the algorithm is 70 %
sure that it is the correct face for the given person. However, I may be
mistaken in this supposition. Because the progress bar seems to be a scale
that goes from "Sensitivity" in one end and "Specificity" in the other end.
I am not entirely sure how to interpret that....

But suppose I am right, then increasing this setting to, say, 90 or 100 %
should result in *fewer* matches for each person. But the found matches
would have a high probability of being correct.
Likewise, decreasing it to, say, 20 % should *increase* the number of
matches. But the found matches may contain a lot of spurious hits.

THis is not what I experience, howerver. I have mostly had this setting be
on 70 % which is default. Then I noticed some persons for which I have very
few photos, they seem to get a LOT of matches. For example. I have a person
who I only have 2 photos of. But DK has found over 1300 matches of her. And
they are ALL spurious hits.

So I went to settings and set it to 90 % and then re-ran the "SCAn
collection for faces" process.

When the process finished, thre we still thousands of hits for her. I would
expect that that unconfirmed hits for this person would have gone down
drastically.

What am I doing wrong?

Or am I misunderstanding how this feature works?
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