Monday, September 16, 2013

Cars, Cameras, and Computers: License Plates for the 21st Century

Soon after we moved from Texas to Massachusetts in 1983, I went to the Registry of Motor Vehicles (which we always referred to thereafter as the Registry of Woes, but that's another story) and got Massachusetts license plates.  Ours had some fairly typical arrangement of letters and numbers (e. g. HGQ 796), but as we spent more time there, I began to notice that a few cars had plates with only three digits, or maybe two:  "967" or "76."  It took some asking around to discover what was so special about those plates, but eventually I found out.

Turns out that those two- and three-digit plates were handed down from generation to generation, possibly even bequeathed in wills.  You see, Massachusetts was the first state in the nation to issue license plates, in 1903, and the first plates did have only two or three digits.  Somewhere along the line, the bluebloods who owned the first cars with license plates decided that some visible trace of this distinction should be left to their descendants.  So they evidently spoke with their buddies in the legislature to allow these old plate numbers to be passed to younger relatives.  So eighty years later, any latecomers to Massachusetts (and never mind if you moved there as a three-month-old, that makes you a latecomer) could look around and tell which drivers were descended from families old enough, and presumably rich enough, to have owned one of the first cars in the Commonwealth. 

I don't know if this curious habit continues there today, but if it does, it looks like Massachusetts may have to figure out a way to tell computers about the achievements of remote ancestors as well as people.  There is a good chance that everyone's license plate in the near future will have not only visible characters, readable easily by humans and with some difficulty by machines, but will also bear an invisible barcode that is much easier to read by machine than the visible characters are. 

Most people know that computers can read license-plate numbers by now almost as well as people can.  These devices, known as Automated License Plate Readers (ALPR for short) use a digital camera and a series of algorithms to separate the alphanumeric characters from the background, which task is increasingly challenging these days when custom plates have pictures of everything from blue whales to your favorite grandchild.  Once that's done, the algorithms interpret the characters and send the result to law-enforcement officials or whoever is interested.  These ALPR devices are used in automated tollbooths on toll roads, as well as their more controversial use in camera-equipped traffic signals that generate tickets for people who run red lights. 

But ALPR does not read the plates correctly 100% of the time, and so 3M and other firms have developed a type of infrared-readable ink that can be used to print a certain form of bar code directly over the visible image on the plate.  3M claims that the invisible barcode is much more reliably read by automatic bar-code readers than the visible characters, and at least one state (Virginia) is seriously considering adopting the machine-readable barcodes.  I have heard a rumor (which was the inspiration of this blog, incidentally) that many if not most states already use them, but I have not been able to confirm this rumor.  It may be the sort of thing that some states would prefer not to be known, anyway. 

We Americans are very attached to our cars, partly because the automobile is perhaps the single most significant technology that enables millions to live more independent lives in many senses.  The mobility permitted by the automobile has altered much of the country's built environment and contributes to the sense of freedom symbolized in movies when a solitary car speeds away from the camera down a lonely desert road. 

Anything that compromises the privacy of the very private space represented by the automobile tends to get our attention.  Many new cars now carry in their onboard computers a system that amounts to a "black box" which records data on control settings, acceleration, and other information that is of interest to insurance companies and lawyers in the event of an accident involving the vehicle.  And now that many cars come with GPS and wireless transceivers, not to mention the cellphones people carry, it is no long stretch of the imagination to picture a Big-Brother government knowing exactly which checkpoints you passed when, any time it wants.  The technology is already largely in place.

But in a way, the invisible-ink barcode idea is only applying to automobiles what we have already applied to our persons.  We are long since used to carrying forms of personal identification that are designed to be read by both humans and machines.  The magnetic strips on your credit cards, the RFID chips in your driver license (that's the way Texas refers to it, not as a "driver's license") and possibly a company or university ID card, and the cellphone in your pocket that is kept track of by your phone company are earlier steps in this direction.  There has been a lot of speculation (including an article that I contributed to in a professional magazine) that sooner or later, having some sort of RFID chip permanently implanted in your body will either become popular as a voluntary form of self-imposed cyborgism, or will be required by the state at some point.

Compared to having an RFID chip implanted on your person, letting your state's motor vehicle office put invisible ink on your license plate is not that big a deal.  From a technical point of view, it's just an incremental improvement that will simplify and improve the accuracy of machines that read license plates.  But the very fact that someone thought it interesting enough to spread a rumor about it says that invisible ink on license plates may cross another invisible line on the way to a future that not all of us would like to see happen.

Sources:  In 2012, the Commonwealth of Virginia (that's how some former colonies refer to themselves) commissioned a study of license plates that mentions the invisible-ink-barcode technology, and is downloadable at$FILE/RD383.pdf.
The 3M firm has a news item on a "license-plate shootout" field test of various ID technologies, including their own, at one of the longest URLs I've ever seen:  And I also referred to the Wikipedia article on "vehicle registration plates."  The magazine article I contributed to appeared in Proceedings of the IEEE, "Social implications of technology:  the past, the present, and the future," vol. 100, pp. 1752-1781, May 2012.

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