Album Artwork

Back in November I got my first iPad and after syncing my music library I discovered that a LOT of my album artwork was in need of updating. A lot of it was old and low resolution. I realized it would take forever to check and update my entire library, so I decided to start with a few select albums and spent a few days updating them with newer, higher resolution artwork. Once I was done I did a sync to both my iPad and iPhone, but thats when the trouble started. Some of the new artwork transfered, some didn't. On some albums, the new artwork is only present for some songs, others retained the old artwork. I noticed that the issues were identical on both my iPhone and iPad (as far as which albums/songs were updated). The really infuriating problem is that a lot of my hard work seems to have been reversed. After syncing I went back to iTunes and discovered that a lot of the new high res images had beed replaced with the old low res images I had deleted, or thought I had. W T F am I doing wrong here? I'm also using iTunes Match, would that possibly have something to do with it? I noticed that the artwork issues I am having with both my iPhone and iPad are also present when pulling up iTunes Match on the AppleTV. Anyone have any suggestions on how to get new artwork synced across everything without it deleting my work in the process? I'm syncing from iTunes 11 on a MacBook Pro running 10.8, both iPhone and iPad are running iOS 6.0.2.

Thanks!!

G