2.3.4 ?  possible

In older version is possible via FTP upload folder with photos and subfolder "thumbnail" and files TN-*.jpg generated automatic with Piwigo

In new version is this not possible.
When i local make subfolder "thumbnail" and all thumbnails with regular name TN-*.jpg - this metod also working not!

Since 2.4, Piwigo has an automatic generation system for thumbnails and other resized pictures. Piwigo calls i.php to generate the resized picture in ./_data/i/, then directly calls the resized picture from ./_data/i/.

As said in posts on this forum where you should have searched, you can generate locally as you used to.

Thumbnails generatet also Piwigo 2.5.2,
but with too low quality !
??

Where i can setting qualitty of automatic thumbnails ?

I do understand your problem, but you doesn't seems to understand what I say

Before you were generating offline, now Piwigo has the possibility, the feature, to generate online and on the fly, BUT you can still do you thumbnails and other sizes offline and upload them in /_data/i/

Your settings seems correct: you can
-delete the bad generated pitures in /_data/i/... and try to re-generate them by changing Sharpen or Image Quality
-generate on your computer like before

Any specificities of the original pictures? like the color space?

You could try to update the Imagemagik version or try with $conf['graphics_library'] = 'gd'; as a local configuration (check the doc)

puschpull wrote:

now i test:
Piwigo 2.3.4
the same photos, the same webhosting, all thumbnails is OK

http://l_test.puschpull.org/index.php?/category/3

how did you generated them?