barely visible UserID in postbit for security

[MattLuria]

I operate a gaming alliance webforum and having people create false ids to gain access is normal part of the game. What I am wanting to do is have when a user is viewing a page in the postbits, I would like the current viewer of the thread to have their userid barely visible in the post so when screen shots are made of the boards, we can off colorize the screen shot to see who took the screen shot.

Our boards use the similiar color green that the vb.org site uses as well if that helps.

Just to explain a bit better

puts the member ID in the user's post as the same color as the background of the forums so It's the member ID of the person reading the post hidden in all the posts.

[Wired1]

So you want to watermark the forum with the userID? Hrm, you may want to do something like a binary pixel change, so that the ID is represented as on/off pixels, or change their userID to hex, and have that show on the forum somewhere.

[MattLuria]

Would you have any idea on how to do that?

Espionage is a part of the game that we play however, I'd like to prevent it if at all possible.