[pkscout]

Are you saying you think version 3 of Artist Slideshow supports album art?  It doesn't.  No version of AS supports downloading album art.  I think there might be a couple places where it loads an image URL for the skin to use, but I'm not even sure those work anymore (especially if they are from last.fm).

From the AS wiki: Alums can have Album images. Just asking about the number of and names, any name and number?

7.1 Directory Structure
To override the downloaded information, you need to create another directory in the folder you defined in the settings as the Local artist folder. Your folder structure will look something like this:
<artistname>
extrafanart
override
albums (folder with artist album art)
albumname.jpg (any XBMC image type supported)
anotheralbumname.jpg

Ah, I didn't realize you were doing overrides.  One album image named with the album name. You can use any image extension Kodi supports.