Large Artwork of 1,000 Pixel is about 1Mb and sometimes even smaller than that 600 Pixel Artwork is about 200kb.

For a 15 Track Album even with Artwork embedded in the Track file you are looking at about 16 by 200k = 3.5Mb per Album.

Even large Artwork will only be a very small percentage of e.g. 350Mb Albums.

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