Hi Serge!  Some questions:  1) have you deleted any of the images from your library? Are they still there?  2) for the pixelated ones, have you tried zooming all the way out and back in again? This can sometimes force Roll20AM to use the proper optimized version of the image.  3) (less likely) deleting cache and cookies and then sign out and back in again. If this causes even the pixelated ones to disappear, then the problem points to deleted library images.