piespy said:
I'm logged in and can see the pic; but probably Danbooru's http agent isn't and only gets a 403.

Does it really work for you to put the image URL in the upload form and submit? I've tried several times with different pics and it always failed: "Preview couldn't be generated (error code 4)".

It seems you're using the upload form of danbooru. As far as I know, that wouldn't work. Danbooruup, on the other hand, works like a charm. I was under the impression that you were using danbooruup.

jxh2154 said:
I'd think that using pixiv as the source URL is a bad idea if you have to sign up for the site. At the very least, when it's just as easy to get it from the artist's site, that seems better.

The user name folder of the artist is pretty static (unlike their profile nickname) so I don't think there's a problem. Also, I use Pixiv as a last resort; the artist homepage always comes first.

surasshu said:
Perhaps a "Pixiv number" section on the artist form would be a good idea?

That would be too site-specific. Then again, if I remember correctly, the fc2 blogs already have site-specific code in danbooru.