Doesn't matter. Gimp is insanely hard to use. This isn't.

I guess you've never actually used gimp.

Because this is exactly how the gimp tool works - you highlight the foreground, background areas and it shows you in real time what it's picking.

It's so similar to it I was wondering if it actually IS it (behind the scenes).

GIMP doesn't give you a realtime boundary like this does, nor a preview image. I've done a lot of alpha matting in The GIMP and this seems far quicker to get similar results (except the up/download for me).

For quick and dirty work I'd use this for sure but revert to a desktop tool for precision work I think.

Does anyone know other Linux tools, or online for that, that do this comparatively well?

> GIMP doesn't give you a realtime boundary like this does, nor a preview image.

Yes it does. Look at the link in my post - Figure 14.33. The dark blue area is the background that will be removed.

I use The GIMP for these sorts of things, the boundary is not realtime in the same way. As you select using the foreground or bg paint, the boundary doesn't change immediately. Instead it waits until you've finished painting, un-click and then it processes - it's a minor but significant difference in UX.

It's not, we developed it from scratch w/o knowledge of the gimp feature. (I'm one of the devs).

Did you use the SIOX algorithm to implement it? That's what the Gimp feature is based on: http://www.siox.org/