Which artwork formats are supported by the iPods?

Hello,

The image (if any) that is displayed when a song is played is called the artwork. Can anyone tell me which artwork formats (jpg, etc.) are supported by the (Music/iTunes app on the) iPods? I need the info to go back to at least the iPod Touch.

And are there any other restrictions (size, resolution)?

Thanks in advance.
Which artwork formats are supported by the iPods?
 
 
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