Since iTunes 8 was released it has been possible to view your iTunes music, movies and TV shows in grid view (Command-Option-4 or in the View menu). Once in grid view, if you choose to group items by genre you will see that Apple has provided some pictures for commonly used genres. Unfortunately there are not a lot, however Apple has made it so similar genres appear under the same image. For example, there is no image for Rap, but iTunes automatically gives this genre the Hip-Hop image.

If you aren't happy with the artwork provided, or you want to add your own genres, you can do this fairly easily by adding an image to the iTunes package, and then editing a plist file to pair it to the genre. Here's the step by step process.

Start by going to your applications folder and finding iTunes. Right-click (Control-click) on it, and choose "Show Package Contents" from the menu. In the folder that appears, navigate to the Resources folder. This is where you will find everything you need to change.

All the jpg images with names like genre-XXXXX.jpg are the artwork files. Note that all the movie ones end in M, and ones especially for TV Shows end in T. If you want to edit one, hold the option key and drag it to your desktop to copy it there. Once you are done editing, save the file to the desktop and the drag it back to the Resources folder. I would suggest you don't replace the old image, just in case you want to go back to it. Simply rename the old one to oldgenre-XXXX.jpg or something similar.

If you want to create your own genre artwork, note that all the movie genres are 171px x 256px and all the TV show and music genres are 256px x 256px. If you create artwork that isn’t the right size, iTunes will automatically scale it for you anyway, so you don’t need to worry about this too much. Also note that you don't have to round the corners yourself, iTunes does this for you. When copying the file to the iTunes resources folder, make sure to give it a name different from any existing genre images.

If creating your own isn't your thing, a quick search on google brought up a flickr group containing artwork others have created.

The next step is to get iTunes to use your image automatically when you use certain genres. In the Resources folder, look for the file genres.plist. Before we make any chages to this file, you might want to back it up. Once you've done this, open it up in TextEdit (Right-click and choose Open With TextEdit). This will pretty much look like nonsense to anyone unfamiliar with plists, but don't worry. You will notice that most of the file is made up of the following lines, repeated over and over again:

<dict>
<key>matchString</key><string>action</string>
<key>resourceFile</key><string>genre-actionM.jpg</string>
<key>kind</key><string>movie</string>
</dict>

This one looks out for any "movie" with the genre "action" and gives it the image "genre-actionM.jpg". You may notice that some other ones are slightly different. Most TV show and music genres don't have the final line. The one that does is the TV show genre "Classic" which also has the line <key>exactStringMatch</key><rue/>. This is to make sure it doesn't get mixed up with the music genre classical.

Say, for example, you created some genre artwork for Gothic Rock, and called it genre-gothicrock.jpg. After the last </dict> in the file, you would write:

<dict>
<key>matchString</key><string>Gothic Rock</string>
<key>resourceFile</key><string>genre-gothicrock.jpg</string>
</dict>

For movie genres you would also include the line <key>kind</key><string>movie</string>.

Save the file, the quit and re-open iTunes. If everything worked, your genre artwork should show up in grid view. If it doesn't, the most likely problem is typos in the genres.plist file.

One more thing to note is that you might lose your changes when iTunes updates. You might want to keep a backup of your new jpg artwork images and the genres.plist file in a separate place as items within the package contents are often replaced when the application updates.