v41 - thumbnail caching system - thumbnail size and compression [Fixed]

[masterjp]

The thumbnail caching system sometimes doesn't make sense to me or seem illogical.
I think it uses Android or other programming libraries.
The thumbnails are stored as JPEG format file with around 90% quality in the hidden folder Pictures\.Thumbnails in the internal storage. That’s fine.
A higher compression with 80-85% quality would be good to save more space and boost up the loading time for thumbnails.
Actually XnView does it very well and faster than many other freeware gallerys (e.g. fossify gallery, ReFra, etc.)!
But if your photo gallery is very big or you use a slow android device (e.g. Android TV box) with less RAM you feel the difference of big or small thumbnails. A+ gallery for example use very small thumbnails and is lightning fast. So I can compare different apps and loading behaviours.
In my opion XnView will get more performance with a small step and I hope with a less work.

I have many different gallery apps installed for special use case (e.g. editing, color filters, etc). Every gallery app use their own thumbnail system and save the data in their own hidden folder which you can not be modify without root rights.

XnView thumbnail files are fantastic small (resolution up to 1000 pixels and less than 100 KB) and others are 150-300 KiB (up to 2300 pixels).
I understand, that jpeg compression sometimes need more filesize for pictures with complex texture or many colors.
Is it possible to general limit the thumbnail size e.g. to maximum 1.000 pixels? I think it is enough for smartphone and tablets or android TV boxes.

[xnview]

i don't create thumbnails in Pictures\.Thumbnails, it's android

[Kadet]

Now that this topic has been brought up...
This selection of the maximum width/height size actually looks strange. No rule can be found.
In my opinion, 400px is enough as the maximum size.

Since this application supports the JPEG XL format, it is JXL that should be used with a quality of 85 and a speed of 5.

[masterjp]

Okay, if Android is the reason for the large thumbnail image files, the only thing we can do is take matters into our own hands: use XnView to batch-resize the images on the PC and then use JPEG-LI for destination file to adjust them to the desired file size. I've already tested this myself, and it works really well! It's just a hassle to check every time which files have already been converted. But that's my problem.