Have you noticed those strange black and white grids - like demented crosswords - popping up around the place? In newspapers, flyers and the like? No? Well, I have. And I dare say if I lived in Japan I'd have seen them on T-shirts, coffee mugs and a whole lot more.

They're 2D barcodes for your mobile device (primarily phones). You take a photo with the built-in camera and the onboard software automatically extracts some text, a phone number or a link. (If your phone is a bit older, you can download the software from your manufacturer.)

I've been playing around with these mobile codes (QR codes and Datamatrix) for the past few weeks, thinking of things to do with them. As a starting point, Nokia's handy webservice for creating the images needed to meet our friends at Yahoo Pipes.

The result is Mbarcode URL. It's run along the same lines as Embiggen TinyURL: there's a page where you can see it working, plus a bookmarklet for browsers and a button for publishers.

Go on, give it a click! (Click anywhere on the popup to close it.)




One of the limitations with the QR and Datamatrix codes is there's a limit to how much you can pack in. As it gets bigger, the blocks get smaller and the decoding error rate grows. This limits the effective size of a URL to around 50 characters - even less if you want to be robust.

So behind the scenes, Mbarcode uses TinyURL to shorten the target link into something much more compact. Now you don't have to worry about the size. As a result, you can use the data: URI scheme to pack as much into your mobile codes as you want. I've "compressed" a 10K PNG image into a QR code using this approach, effectively achieving far higher resolution than you deserve with a mobile phone camera. Neat.

What's the point? Not sure, really. Here's a couple of ideas:

• You're browsing along on your desktop and you want to send a link to your phone for when you're out and about later. Click the bookmarklet, point your phone at the screen, take a snap. Done. It's in your phone.



• You're out with a cool friend who owns an iPhone with GPS. She's checking out nearby bars on Google Maps. You'd like to look too, but while your phone has a web connection, it has no GPS. What are you going to do? Laboriously type the address or longitude/latitude into Google Maps? No! You're friend clicks the bookmarklet, it creates the QR code, you snap her screen with your phone and now you're both browsing the current location!

Yeah, it's not a lot, but it's still fun to play. Maybe more uses will come later, especially if I figure out what to do with the cool experimental online barcode decoder at ZXing.

Suggestions?

Filed in: webtech, hacks, tinyURL, bookmarklets