Step 1: Background.
But haven't you ever suspected that some clever bugger somewhere could undo it? We've all seen those spy films where they keep enhancing passport-sized photos until they can see the faces of people reflected in the subject's pupils...
Maybe I'm just being paranoid, but K.U.P.I.D. is a guaranteed barrier to such processes.
Step 2: Materials and equipment.
> Access to a PC and printer (which you already have, or you wouldn't be reading this, would you?)
> Sticky stuff.
> A sharp thing.
> A head-sized box.
Step 3: The Secret.
Use the graphic software of your choice to produce a pattern of randomly-tinted blocks, and print it out several times.
Step 4: Construction.
Now the trick:
Put the box on your head!
That's it, you're done. Nobody can tell who you are, no matter how sophisticated their software.
What do you mean, you can't see?
That's what the Sharp Thing is for - poke holes level with your eyes (but please, remember to take the box off before you start sticking Sharp Things into it at eye-level...