This information is found in iTunes Cover Flow data files.
Tag ID Tag Name Writable Values / Notes 'data' ImageData N (embedded JPEG or PNG image, depending on ImageType) 'itch' Itch - --> ITC Header Tags 'item' Item - --> ITC Item Tags 
Index Tag Name Writable Values / Notes 16 DataType N 'artw' = Artwork 
Index Tag Name Writable Values / Notes 0 LibraryID N 2 TrackID N 4 DataLocation N 'down' = Downloaded Separately 
'locl' = Local Music File5 ImageType N "\x00\x00\x00\x0d" = JPEG 
'PNGf' = PNG7 ImageWidth N 8 ImageHeight N