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Pens and Needles: History's Strangest (and most useful?!) Tattoos

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If Momma refuses to let you spend your allowance at the tattoo parlor, maybe you should drop some history, and let her know just how "useful" a tattoo can be.

Tattoos as Telegraphs
The Tattoo: secret messages
The Tattooed: slaves
The Reason: It beats paying for postage
According to Greek Historians, back in 312 BC, Greeks used to shave the hair off their slaves, tattoo a message into the back of their heads, and then wait for the locks to grow back. Once the message was all covered in hair, they'd pack the slave off, and send him running.

ink-8427.jpegTattoos for Mercy
The Tattoo: a crucifixion scene
The Tattooed: troublemakers in the British Navy
The Reason: To get out of being whipped
There's a reason Eminem and Snoop both suited up for their court appearances. Similarly, British mischief-makers used to get "Jesus on the cross" inked onto their shoulders to make themselves seem like upstanding citizens. That way, if a religious captain was somehow moved by the WWJD message, he might drop the whip in favor of a lesser punishment.

miketyson.jpgTattoos to Intimidate Boxers

The Tattoo: A tribal-looking thing
The Tattooed: Mike Tyson's face
The Reason: To honor the Mayans?
Claiming he was into history, Iron Mike made the unfortunate mistake of telling reporters that his new face tattoo was a Mayan New Zealand symbol. The fact that Mayans aren't really from New Zealand didn't stop his enthusiasm. Of course, history is the least of Mike's concerns. According to Sports Illustrated, the former heavyweight is currently trying to fight women in the ring.

valpop1.jpgTattoos as Punishment
The Tattoo: a vagina on the forehead
The Tattooed: lusty Indian priests
The Reason: To make an example of 'em.
If you thought laws were severe in Texas, any priest caught with his trousers down in ancient India got a "little girl" branded into his noggin.

tatoo-golden-palace.jpg Tattoos as Billboards
The Tattoo: GoldenPalace.Com, also on the forehead
The Tattooed: Karolyne Smith
The Reason: Cash money
In need of some quick cash, Karolyne Smith did the first thing any enterprising young American would do, and auctioned off her forehead on e-Bay. After 27,000 visits, online casino GoldenPalace.com outbid everyone with a cool $10,000 offer. Each letter on her forehead is an inch high, and the terms are that she has to leave it there permanently. Still, it beats having a vagina on there.

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iStock // Ekaterina Minaeva
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Man Buys Two Metric Tons of LEGO Bricks; Sorts Them Via Machine Learning
May 21, 2017
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iStock // Ekaterina Minaeva

Jacques Mattheij made a small, but awesome, mistake. He went on eBay one evening and bid on a bunch of bulk LEGO brick auctions, then went to sleep. Upon waking, he discovered that he was the high bidder on many, and was now the proud owner of two tons of LEGO bricks. (This is about 4400 pounds.) He wrote, "[L]esson 1: if you win almost all bids you are bidding too high."

Mattheij had noticed that bulk, unsorted bricks sell for something like €10/kilogram, whereas sets are roughly €40/kg and rare parts go for up to €100/kg. Much of the value of the bricks is in their sorting. If he could reduce the entropy of these bins of unsorted bricks, he could make a tidy profit. While many people do this work by hand, the problem is enormous—just the kind of challenge for a computer. Mattheij writes:

There are 38000+ shapes and there are 100+ possible shades of color (you can roughly tell how old someone is by asking them what lego colors they remember from their youth).

In the following months, Mattheij built a proof-of-concept sorting system using, of course, LEGO. He broke the problem down into a series of sub-problems (including "feeding LEGO reliably from a hopper is surprisingly hard," one of those facts of nature that will stymie even the best system design). After tinkering with the prototype at length, he expanded the system to a surprisingly complex system of conveyer belts (powered by a home treadmill), various pieces of cabinetry, and "copious quantities of crazy glue."

Here's a video showing the current system running at low speed:

The key part of the system was running the bricks past a camera paired with a computer running a neural net-based image classifier. That allows the computer (when sufficiently trained on brick images) to recognize bricks and thus categorize them by color, shape, or other parameters. Remember that as bricks pass by, they can be in any orientation, can be dirty, can even be stuck to other pieces. So having a flexible software system is key to recognizing—in a fraction of a second—what a given brick is, in order to sort it out. When a match is found, a jet of compressed air pops the piece off the conveyer belt and into a waiting bin.

After much experimentation, Mattheij rewrote the software (several times in fact) to accomplish a variety of basic tasks. At its core, the system takes images from a webcam and feeds them to a neural network to do the classification. Of course, the neural net needs to be "trained" by showing it lots of images, and telling it what those images represent. Mattheij's breakthrough was allowing the machine to effectively train itself, with guidance: Running pieces through allows the system to take its own photos, make a guess, and build on that guess. As long as Mattheij corrects the incorrect guesses, he ends up with a decent (and self-reinforcing) corpus of training data. As the machine continues running, it can rack up more training, allowing it to recognize a broad variety of pieces on the fly.

Here's another video, focusing on how the pieces move on conveyer belts (running at slow speed so puny humans can follow). You can also see the air jets in action:

In an email interview, Mattheij told Mental Floss that the system currently sorts LEGO bricks into more than 50 categories. It can also be run in a color-sorting mode to bin the parts across 12 color groups. (Thus at present you'd likely do a two-pass sort on the bricks: once for shape, then a separate pass for color.) He continues to refine the system, with a focus on making its recognition abilities faster. At some point down the line, he plans to make the software portion open source. You're on your own as far as building conveyer belts, bins, and so forth.

Check out Mattheij's writeup in two parts for more information. It starts with an overview of the story, followed up with a deep dive on the software. He's also tweeting about the project (among other things). And if you look around a bit, you'll find bulk LEGO brick auctions online—it's definitely a thing!

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May 23, 2017
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