I have this problem - http://forum.coppermine-gallery.net/index.php/topic,3421.0.html
It's written there that there is no way to resize thumbnals (with fixed both witdh and height). But look at that - http://www.britneyres.com - I'm sure their thumbnails are resized automatically! Can someeone tell me how to make it?
That thread's 4 years old. That site sets the thumbnail dimensions in the theme which means the thumbnails are distorted. I think the modpack supports proper fixed sized thumbnails, try that.
Thank you very much!