It doesn´t influence old pictures. Sometimes width does, but only HTML resize, not real resize.

There is a image cache delete tweak here at forum, use search.

 

With this tweak you delete all cache and at page refresh (front) you regenerate all pictures with new rules.

Be careful not to delete pictures from "src" folder. It is painful if you do this.

Yeah I'd already use the cache tweak :)

 

Thanks again for your help ;)

getk2.org/community/New-to-K2-Ask-here-first/134021-creat-thumbnail-by-width-and-height-you-can-input-height-value-on-K2-control-center#134025

i tried your initial code, i just want square thumb i don't want to define height
it works great, it works for category thumbs too (category.php)

in this years do you noticed some bugs?