An Invisible Marking System Your Phone Scans

Technology is beginning to be embraced more and more by magicians as the methods are becoming more reliable.

The second key thing that's changing when it comes to tech and magic is the type of tricks magicians are performing with technology. The community has learned to use such methods in more invisible or organic ways. This brings us neatly to the third key reason magicians are starting to embrace technology – the world around us is embracing technology, too.

With people becoming more likely to carry phones than cash, pens, pads, and purses, it's feeling less and less unusual to incorporate your phone or theirs into your magic.

It's also very hard not to feel excited by some of the methods that rely on technology. Let's look at some details of a marking system two coders shared online. The deck below has a visible barcode printed on it. Scanning the barcode will reveal where every card is within the deck (or isn’t — if cards are missing).

A camera scans the deck and feeds the data into software that can tell you whatever you like based on the information. I hope your minds are already going wild with possible applications.

A marked deck was released that used a somewhat similar principle many years ago. The marking was fast enough to be read by the human eye and would only tell you which card had been selected. The brilliant thing about that trick release was that the markings were printed with special invisible UV inks. So they were invisible to the human eye until lit by a specific LED light.

Ah, it looks like these clever coders also thought of that.

One of the decks above is unmarked, and the other has a barcode printed with invisible inks. The infrared ink is only visible under special infrared conditions.

While I think magicians could happily hide one edge of the deck from view, this significantly improves the magic. You can mark both sides of the deck with the same barcode so you can easily hand the cards out for inspection and shuffling.

This small device is a Raspberry Pi Zero W with a NoIR camera. It can see the invisible markings on the card. See that shiny circle — that’s the special IR filter. A scanning server runs on this small device.

It’s tiny—how wonderful. It probably costs a fortune. Nope, the Raspberry Pi Zero W is ten bucks and easy enough to palm. It will send any data to you via Bluetooth.

This screenshot is of Abra, an iOS client application on an iPad. It could just as quickly run on a phone. You can see how clear the tiny infrared camera can see the barcode. I want to take a moment to remind you this is all on Github, and you can start building with this today.

Knowing which card is selected and removed from a deck is an obvious application. But this would also allow for some brilliant memorization routines, cards at any number, and playing card location effects. I’m here to tell you that an audience can shuffle a deck as much as they like, and you will instantly know the order without even touching the deck.

If you don’t want to spend ten bucks on that little palmable camera, you can always use your iPhone or iPad camera – as seen in the header image for this article.

These iDevices can't see infrared marks by default, even with special filters. However, they can see black ink marks and marks made using a different type of invisible ink - ultraviolet fluorescing ink.

It’s not too difficult for you to take back a shuffled deck and hold it momentarily below the table. Upon doing so, a camera and UV light below the table do all the work. Heck, this could be done off-stage by an assistant who needs to instantly find out which card was removed from a deck of cards.

It can scan/decode a 1080p image to an ordered deck in as little as 4ms. Hot dam. If you’d like to play with the code, which Paul Nettle and Jeroen Van Goey shared, here are all the details.