Change the line in the file admin-functions.php
from :
@imagecopyresized ($thumbnail, $image, 0, 0, 0, 0, $image_new_width, $image_new_height, $image_attr[0], $image_attr[1]);
to
@imagecopyresampled ($thumbnail, $image, 0, 0, 0, 0, $image_new_width, $image_new_height, $image_attr[0], $image_attr[1]);
“imagecopyresampled” does a LOT better job than ” imagecopyresized “
Hope this works + helps!
I was also having problems with thumbnail quality and didn’t like the switch from MT to wordpress for that reason. Maybe this can get in a new update.
–Kevin