I cannot find the duplicate of a photo

[frankdarwin]

In the category Duplicate, I am shown a photo "Ausflug.....jpg") (see Category Duplicate.jpg).
This photo has a version.The original (see "Bild Original.jpg") differs from the version
The original is different from the version (see "Bild bearbeitet.jpg") because I have edited the original.
When I search for the duplicate with "Search Duplicates", no duplicate is found (see "search result.jpg").
The database diagnosis reports no error.All metadata is written.
What is the problem?

[jch2103]

Try using 'Visually similar images...'. It only take one byte difference for 'Search duplicates' not to work.

[Mario]

Correct.

See Finding Duplicate Files and Visual Queries for more info.

Binary duplicates (copies), images where the image data is identical (sans the metadata) and visually similar images are quite different.
Processing an image in any way will make it fail all but the visually similar searches.

[frankdarwin]

O.K.
With 'Visually similar images...' the edited version is shown to me as a duplicate.

Does this mean that all versions of a photo that I have only slightly edited (brightness, contrast, etc.) are recognised as duplicates?

I know that I can remove a photo from the category with the shortcut 'U'. Is the removal from the category permanent, or do I have to expect that the edited version of a photo will be recognised as a duplicate again at some point?

[Mario]

Does this mean that all versions of a photo that I have only slightly edited (brightness, contrast, etc.) are recognised as duplicates?

Normally. The algorithms used by IMatch to detect visually similar images are very advanced.
There is no 100% guarantee that IMatch will detect all visually similar images, or at least not at the top spot. That's why you get 5, 10 or 50 images shown in results to pick from.
Even a slight manipulation in an image editor may have drastic consequences on the pixels of your images.

I know that I can remove a photo from the category with the shortcut 'U'. Is the removal from the category permanent, or do I have to expect that the edited version of a photo will be recognised as a duplicate again at some point?

You can remove images from a category that way when you have assigned them to that category manually.
So, unless you assign the image again by yourself, it will not show up in the category.

You cannot unassign images that way from data-driven or formula-based categories.

[frankdarwin]

You cannot unassign images that way from data-driven or formula-based categories.

But this is very confusing. So this means that all versions of a photo that have been created by minimal manual editing always show up in the category Duplicates.

Which photos appear in the Duplicates category?
Duplicates, Copies, Visual similar images?

[Mario]

See Searching for Duplicate Files