Graphic validation tutorial

Hi everyone,

i am kinda new to this web development so i would like to ask is there
any pros out there that can teach me a thing or 2 about graphic
validation in ruby on rails.

The furtherest i go is down rmagick which seems to be required to draw
picture in ruby.

But anything after that i need some help/turorial/guidance.

thanks for all the help and trouble from anyone.