Last month I moved from the Matrix (custom) skin to Jupiter (custom). What a great skin!
Now I'm adapting all my albums, and I have one question:
Adapting an album I delete all the pictures in it (because made in Matrix), change Matrix into Jupiter, and check the settings, Then I add the pictures again.
That's a lot of work, and suddenly I thought, maybe that deleting and adding again would be unnessary...
Is that right?
There's no reason to delete and re-add the images. In fact, doing that wipes out whatever titles and comments you've entered, so you're better off leaving the images alone. Between the jAlbum core and the skin, unnecessary output files will be removed, and newly-generated files created, as needed.
Glad you like Jupiter, but I'm surprised you've chosen that one. To me, the natural progression has always been Matrix -> Saturn (both "lightbox" skins, with similar thumbnail layouts), or Gromit -> Jupiter (both "slide page" skins, with similar thumbnail layouts). But whatever works for you!
There is one file that Matrix will leave behind, and that the newer skins won't get rid of. Not a big deal, but after making the album with the new skin, you can open the output directory - Tools > Open Directories > Output directory - and delete any occurrences of mx-theme.jpg. There might be one in each folder of the album, too.
The new theme images will be called ja-theme.jpg, and you should leave those alone!