similar image search not always working as expected

[Daniel Bauer]

Ok, thank you Maik for putting your time on this! :-)

Am 07.05.25 um 07:53 schrieb Maik Qualmann:
> Hi Daniel,
> 
> Thanks for the sample images, I can reproduce the problem with them.
> The cause is still unclear. If I save the PNG file with digiKam as a TIFF or
> again as a PNG file, it works as expected.
> After debugging, I currently see no difference in the 128x128 thumbnails that
> are created before they are processed into signatures.
> Surprisingly, removing the metadata leads to different results. To be
> continued...
> 
> Maik
> 
> Am Dienstag, 6. Mai 2025, 12:27:16 Mitteleuropäische Sommerzeit schrieben Sie:
>> I think we have a similar bug report; I'll have to look for it this evening.
>> In that image set, one image was slightly cropped from the edges and the
>> colors were modified. They were also barely recognized as similar. If you
>> don't mind, send me an image set.
>>
>> Maik
>>
>> Am Dienstag, 6. Mai 2025, 11:52:43 Mitteleuropäische Sommerzeit schrieb
>> Daniel
>> Bauer:
>>> Hello,
>>>
>>> Sometimes similar image search does not show all possible results, even
>>> though I use similarity 55 - 100%. It does find it though with
>>> similarity set to 40%, but then of course it also finds a lot of false
>>> positives.
>>>
>>> Besides of file format and size the two images are identical, actually
>>> the image used for the search is just a smaller .jpg-version made from
>>> the .png original with a small added watermark.
>>>
>>> Over this night I let digikam rebuild all "fingerprints", but even after
>>> a restart of dk if doesn't find those images when set to 50 or 55%.
>>>
>>> Is there a problem with .png files? (although it happens only with few
>>> images, other .png's of other images are found)
>>> Can I better the results with any trick?
>>>
>>> I can provide access to sample images in private, but those are nudes...
>>>
>>> Kind regards
>>>
>>> Daniel
>>>
>>> (I often use this function to find the original file or a published
>>> version without having to go through the albums with countless photos,
>>> even more when I forgot the name of a model :-) )
> 
> 
> 
> 

-- 
Daniel Bauer photographer Basel Málaga
Twitter: @Marsfotografo (often explicit nudes)
https://www.patreon.com/danielbauer
https://www.daniel-bauer.com (nudes)