How to mask images?

BlitzMax Forums/BlitzMax Beginners Area/How to mask images?

What I want to say, why buy something when you have a free and legal alternative?
It's just a matter of taste I think. I prefer making my artwork into Flash and Swift3D (I know this sounds strange) and for the rest I use GIMP or Teal.

But back to masking images :-). Diordna said something about fuzzy mask, halo's and anti-allised images. Apparently I have no trouble at al masking anti-allised images but that's not what Diordna wanted to say isn't it? So what are fuzzy masks?