Adding non-embedded album artwork

Question

Whenever I have iTunes automatically download album covers it downloads one copy to the PC and associates all relevant mp3 files to that artwork image file.
This is great but only works for like 75% of my music.
When I try to add missing artwork to my other mp3 files, it doesn't add them to the iTunes library downloads, but rather it seems to embed the artwork in the actual file. I do not want this...I'd rather have smaller mp3s without artwork embedded in the actual file.
How can I add artwork through iTunes to display with the mp3s without embedding them, just like the iTunes auto-add feature does?

Answer 1

That's a shame if you really can't.
I would have thought that there would be some way to add artwork locally to iTunes rather than embed the graphics in the actual mp3 file.
I had tried looking into where the info was stored that tells iTunes where the images are, but that didn't work.
Each artwork file is in the iTunes library folder, but they have some alpha-numeric labeling system. I thought the "iTunes Music Library.xml" would hold the info...but if it does it's not straightforward even though you can open the file in notepad and read it easily. All other mp3 info is pretty straightforward in the file...just not the artwork. But even if I could figure out a way to tell iTunes where the artwork is, there's still the problem of format. iTunes downloaded artwork aren't simple jpegs. They have a "*.itc" extension (for iTunes cover?), and normal image viewers failed to open them.