[support] captcha module

[Roger]

I saw somewhere about using images with captcha or something like that 
where I can have an image and ask for some detail within the image to be 
the login.
I've lost the link can someone advise please.

Basically I want to put an image on the log in page. Only members would 
be able, hopefully to recognise a feature within the image/photo/scene 
and enter the description in a field which would form both the user name 
and password for member login to the site.
Thank you in advance
Roger