NextGen certainly has it’s issues, but it seems to be the only game in town. I’ve had problems on a couple different sites with the tumbnails appearing stretched or blurry. This happens when I try to change the thumbnail size from the standard. I’ve regenerated those thumbnails, but they just don’t display properly. The images end up looking stretched or blurry. You need to actually go into the code to fix this – and that means cpanel or ftp access.
Note: Be sure to always backup these files before making changes.
Once you are in your file mananger, you need to access this file:
Go down to approximately line 155 and you will see this code:
// legacy templates expect these dimensions $image_gen_params = array( 'width' => 91, 'height' => 68, 'crop' => TRUE );
Change those dimensions to your new dimensions. You will probably need to refresh a couple times to see the thumbnails properly. Unfortunately, this will get overwritten when you update the plugin, but right now, I don’t know another way around it, so bookmark this page. Let me know if anyone knows of a better way.