How to open/identify ITC2 files?

Hi,

My questions:

1. Anyone know how I can open the .itc2 files? ( located in [user account] -> Music -> iTunes -> Album Artwork )
2. Or convert them to .jpg or .png?
3. Or at least be able to assign to an album, via the "Add Artwork" option, on 'Song Info'? (nothing seems to happen when I tried this)

Backstory

Here's my problem;

I bought some tracks off iTunes, converted them to MP3, but now their album artwork is disappeared. The thing is, its quite a minor band, so I couldn't find the album artwork searching online (not in decent quality at least), however there is the album artwork on it in the iTunes store.

What I've tried;

• "Get Album Artwork" on the song in question, though got the "could not find" error
• Trying to apply a random .itc2 file (in the folders mentioned above), though did not change the album cover
• Tried viewing the album on the web version on the web version of iTunes & "save image as", though it was super low resolution (around 100px square)

Thanks