simply wire round(value/0.5) to the terminal of the ring...
It all depends on your code structure.
Thank you GerdW for your advice. I did as you said and it now responds to my signal.
I've an additional question: since my maximum value is around 3 volts, can i make the picture ring in such way that it shows every additional 0.3 volts the next picture (i've reduced it to 10 pictures)? (and when i'm over 3 volts it still shows the last picture)