So you’ve got a large iTunes library. You go to Advanced, and select “Get Album Artwork.” But once you click on it, you’re notified that iTunes “Could not get artwork for some albums.” You can click on the “total notifications” to see what albums are missing.
Don’t get frustrated. There’s an easy way to add the artwork.
First, go to http://www.allcdcovers.com/. I did not have to register. I simply entered the name of one of the albums that was missing artwork in the “search,” “all covers” box in the upper right. I then found the album, clicked on it, and then selected the front photo. After clicking on it, a new page opens and you have the opportunity to download it. Once you click on it, a new page opens with a large photo of the cover. Right click it, and then save to a folder on your desktop that you create call “Album Artwork.” Be sure to change the title of the file to something that identified it. Once you’ve save it, go to your music library in iTunes and find the album. Select the top song, hit shift, and then tab all the way down to the last song until all the songs in the album are highlighted. Right click, and click “Get Info.”
You’ll get a popup that says “Are you sure you want to edit information for multiple items?” Click yes. Now you’ll see a new window with four tabs. The first tab is “Info,” and it’s open. You’ll notice in the bottom right that there is a selection for Artwork. Double click inside the large Artwork box, and then navigate to your folder where you saved the artwork, and select it and click open. Voila. You’ll now see the artwork.
Update: if allcdcovers.com doesn't have the album artwork, just do a search in Google, but click on "images." You'll find what you're looking for. Save it to the same folder, and then do the above import. Be sure to pick the largest image available (ie, 500 x 500 is better than 250 x 250).
Update Two: In going through the coverflow art, I noticed numerous incorrect album covers that iTunes automatically added, apparently through gracenotes. Some were from completely different artists.