Imge unclonable
It's very a strage use case, but let me say you what it could be interesting to do.

I've writeten a c# app in order to insert a digital sign on pdf documents. It also offer you possibility to add an image which represent user sign on doc.

Well, I'd like to find some solution for manipulate this image, so if someone try to print - cut - scan that image it can't reproduce the same result on final document - emulate my original image sign. 
Surely, no-one can clone my certificate (it's protect by user's smartcard), but generally, all customers will be not carefull to digital sign info (they are much more for skilful useres), instead they alway try looking for inserted image on document and recognize it by some particular. 

I would to find a kind of "digital hologram" or similar.

Any Ideas?
Imge unclonable
===

It's very a strage use case, but let me say you what it could be interesting to do.

I've writeten a c# app in order to insert a digital sign on pdf documents. It also offer you possibility to add an image which represent user sign on doc.

Well, I'd like to find some solution for manipulate this image, so if someone try to print - cut - scan that image it can't reproduce the same result on final document - emulate my original image sign. 
Surely, no-one can clone my certificate (it's protect by user's smartcard), but generally, all customers will be not carefull to digital sign info (they are much more for skilful useres), instead they alway try looking for inserted image on document and recognize it by some particular. 

I would to find a kind of "digital hologram" or similar.

Any Ideas?