Heiya, it's me again about this. ;)
I found out that the default generation of thumbs is tied to the
"$wgImageLimits" AND to the "$wgThumbLimits" configuration setting. If
one for example sets the following for a minimum initial creation of thumbs:
$wgImageLimits = array( array( 320, 240 ) );
$wgThumbLimits = array( 320 );
Result: one gets in minimum five thumbs: 120 (default preview size on
file pages), 180 (default preview size on "Special:ListFiles") as well
as 320 (default size for thumbs), 480 (1.5x of default size for thumbs)
and 640 (2x of default size for thumbs)
If one would change the setting for $wgImageLimits another three thumbs
would be created. To be frank, thumb generation is indeed not
controllable at all.
Am 27.02.2017 um 17:54 schrieb Bartosz Dziewoński:
Other funny sizes probably come from the thumbnails
shown on the file
page itself. For example, for this random file:
The main big thumbnail is 796×600 pixels, and the small thumbnail
under "File history" is 120×90.
Additionally, for every thumbnail, thumbnails with 1.5× and 2× sizes
are generated to be used on devices with high-resolution screens.
And additionally, you can set an arbitrary size for any thumbnail used
in an article, and MediaWiki will dutifully generate a thumbnail of
As far as I know there is currently no option to disallow generation
of thumbnails of arbitrary sizes, and limit it to some preset list.