Hi every one. I came up with something.
I use old eyes optical illusion for marking back design of playing card,
and that system works very well.
You can determine which card is which,
just by looking at the back of card.
Design is very simple, and regular observer can'n see anything,
unless he know the secret.

Name for my marked deck is: Hallucination deck

Here is how look back design of two cards: Ace of spade (Top one), and King of spade (Bottom one)

Click here to view attached image.

This one is King of spade

Click here to view attached image.

I can't see anything? Maybe that is a good thing...

I believe it is

Interesting idea... Some things to consider:

-hard to use with bad lighting or while the cards are in motion... You'll definetively will need some time to study the back of the card to devine it's value and suit, "just one glance" won't do...
-the advantage of the back design is, that it seems to be impossible to hide any markings on it.
-the disadvantage is that it doesn't look like any brand of cards currently sold...

You have right. Card can't be in motion, and this system is not good for playing tables, but for tricks and stuffs like that is ideal. For me 1 or 2 seconds is enough time to find out card identity. One more interesting fact is that when I sometimes reveal the secret to nearest friends and instruct them what to look for, they still can't see markings.

It's clever. Took me a few minutes to spot it

Do you mind to share it with us? In PM if you want to

Thanks Phil J. I'm glad that you like the idea.

I got the markings but had to look a long time. The optical illusion seems to work with these also which is what makes the mark so hard to see. However the OI is pink and the mark is gray if that helps at all.

I would have to do some long winded misdirection and or justification for studying the backs so long though. I do like your thinking. Good luck with these.

Cheers

Thanks everyone for supporting me and mine idea. I am still working on it and when I finish some details I will put all explanations in e-book, and dvd too. If I find how to purashe it I will do that, but maybe that will be little problem because I am from far Bosnia. But I believe that I will have little luck.