I have created a picture password for my account when i installed windows 8 release preview. Also, I enabled the policy "Interactive logon: Do not display last user name" under "Computer Configuration\Windows Settings\Security Settings\Local Policies\Security Options". When I try to sign-in, once I have inserted my username and without filling the password field, I expected that, after clicking on the sign-in options, I had the chance to select the picture password method, unfortunately this was not the case. After clicking on the sign-in options I can click only on two keys pictures, one that, on mouse over, shows "Password" and the other that shows "Microsoft account".

If this is a bug I hope it will be fixed.

Thanks.

Maybe the following thread could help you.

Picture Password not working in windows 8 RP

you can see windows 8 gives you pin, text and picture password for privacy,so you should login with your text password and you can follow the link "listenmefirst.com/create-picture-password-in-windows-8/" to see more in detail where you can resolve your problem.