Tracking Small Changes In Video To See Someone’s Pulse

June 4, 2012 by Brian Benchoff 30 Comments

[Gil] sent in an awesome paper from this year’s SIGGRAPH. It’s a way to detect subtle changes in a video feed from [Hao-Yu Wu, et al.] at the MIT CS and AI lab and Quanta Research. To get a feel for what this paper is about, check out the video and come back when you pick your jaw off the floor.

The project works by detecting and amplifying very small changes in color occurring in several frames of video. From the demo, the researchers were able to detect someone’s pulse by noting the very minute changes in the color of their skin whenever their face is pumped full of blood.

A neat side effect of detecting small changes in color is the ability to also detect motion. In the video, there’s an example of detecting someone’s pulse by exaggerating the expanding artery in someone’s wrist, and the change in a shadow produced by the sun over the course of 15 seconds. This is Batman-level tech here, and we can’t wait to see an OpenCV library for this.

Even though the researchers have shown an extremely limited use case – just pulses and breathing – we’re seeing a whole lot of potential applications. We’d love to see an open source version of this tech turned into a lie detector for the upcoming US presidential debates, and the motion exaggeration is perfect for showing why every sports referee is blind as a bat.

If you want to read the actual paper, here’s the PDF. As always, video after the break.

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Remote Shutter Module Uses LCD Screen For Setup

May 30, 2012 by Mike Szczys 5 Comments

Here’s a full-featured remote shutter project which [Pixel-K] just finished. It seems that he’s interested in taking time-lapse images of the cosmos. Since astrophotography happens outside at night, this presented some special design considerations. He wanted something that he could configure in the dark without zapping his night-vision too much. He also wanted it to be easily configured with a pair of gloves on.

The project enclosure is a 4x AA battery box. He removed the partitions between each cell, leaving plenty of room for the guts. Inside you’ll find a lithium battery and a micro-USB recharger board. It powers the Arduino mini pro which drives the 1.8″ LCD screen and actuates the optoisolator which is responsible for triggering the camera. On the right you can see the clear knob of the clickable rotary encoder. All of the user settings are chosen and selected using just this one knob.

He’s already tried it out on a 6-hour shoot and had no battery life problems or other issues.

OpenCV Knows Where You’re Looking With Eye Tracking

May 30, 2012 by Brian Benchoff 35 Comments

[John] has been working on a video-based eye tracking solution using OpenCV, and we’re loving the progress. [John]’s pupil tracking software can tell anyone exactly where you’re looking and allows for free head movement.

The basic idea behind this build is simple; when looking straight ahead a pupil is perfectly circular. When an eye looks off to one side, a pupil looks more and more like an ellipse to a screen-mounted video camera. By measuring the dimensions of this ellipse, [John]’s software can make a very good guess where the eye is looking. If you want the extremely technical breakdown, here’s an ACM paper going over the technique.

Like the EyeWriter project this build was based on, [John]’s build uses IR LEDs around the edge of a monitor to increase the contrast between the pupil and the iris.

After the break are two videos showing the eyetracker in action. Watching [John]’s project at work is a little creepy, but the good news is a proper eye tracking setup doesn’t require the user to stare at their eye.

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Making Instagram With An Old CRT

May 25, 2012 by Brian Benchoff 14 Comments

If you’re not familiar with Instagram, it’s a mobile app that takes pictures, applies low-fi ‘lomographic’ digital filters, and shares them on the Internet. For reasons we can’t comprehend, Instagram has been wildly successful as of late and was recently purchased by Facebook for a Billion dollars. [Martin Ström] figured he could do something much cooler than applying digital filters to a cell phone picture, so he built InstaCRT, an app that turns your pictures into grainy CRT images and satiates the geek and hipster in everyone.

From [Martin]’s project page, InstaCRT uses a small black and white CRT from an old camcorder and a Canon 7D to apply real-world analog filters to all the uploaded pictures. Once the pictures are uploaded to the MacBook Pro server, they’re displayed on the CRT and a picture is taken with the 7D. Once an Android/iOS device sends a picture to the server, it’s displayed on the CRT, the 7D snaps a picture, and the resulting ‘filtered’ picture is sent back to the mobile device.

While we’re sure a few Hackaday commentors are going to ask ‘why’, it’s still a very cool build that is the first real world digital camera filter we’ve seen. You can check out the video demo of InstaCRT after the break.

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A DSLR Shutter Cable For Android

May 21, 2012 by Mike Szczys 4 Comments

Here’s a very easy way to trigger your DSLR camera using an Android device. It’s a similar method used with IR triggered cameras, in that all you need to do is assemble some simple hardware to plug into the headphone jack. The app that triggers the camera simply plays back a well crafted audio file to do so. The thing that this cable adds is the ability to use the focus feature, since the cable has two data lines.

The hardware is dead-simple. A pair of NPN transistors and a pair of resistors are hosted by this small chunk of strip board. The audio jack for Android uses left and right audio channels to drive the base of these transistors. On the camera side of things the transistors are pulling the focus, and shutter contacts to ground. Once this is covered with shrink tubing it’ll be pretty rugged, and ready to be thrown in your camera bag for use on short notice.

[Thanks Hannes]

3d Printing Saves The Day For Time-lapse Photography

May 15, 2012 by Caleb Kraft 21 Comments

Several of us here at Hackaday have discussed how much we’d like to have some tools, like a 3d printer, but just can’t justify the cost. What would we make? Why do we really need one? Why don’t we just bother [Brian Benchoff] who already has one to make us parts instead. That’s usually how the conversation goes.

[Alexander Weber] gave us another little reason to drop in our “list of reasons we need a 3d printer” list with this little hack. He wanted to play with CHDK but found the camera’s battery unable to stay alive for longer than 2 hours. There is a commercially available adapter to allow you to plug into the wall, but the cost was outrageous. At least it is outrageous to someone who already owns a 3d printer. We just need a few hundred more dollars worth of reasons to justify that sweet 3d printer we’ve been pining over.

[via Adafruit]

Hackaday Links May 9th 2012

May 9, 2012 by Jeremy Cook 18 Comments

Homecut – CNC Cutting Directory

So you have a CNC machine that you use as a hobby, but would like to do some actual work on the side? Or maybe you have an idea you’d like made. Homecut is a map directory where you can maybe hook up with the right person.

The Curta Mechanical Calculator

As [leehart] mentioned in our comments section, the Curta mechanical calculator is a truly ingenious piece of engineering. A quick Google search should find all kinds of information on it, but this article could be a good place to start for some mechanical hacking inspiration!

Luxman Amplifier DAC Upgrade

[R. Barrios] wasn’t happy with using the sound card for his HTPC setup, so decided to add a DAC module onto his reciever. The resulting audio quality was very good, and the build came out quite clean. Check it out if you’re thinking of a hack-upgrade to your stereo equipment.

3D Printable Tilt-Shift Adapter

A tilt-shift lens a neat piece of equipment that is used to make a large scene look like they were miniatures. It’s a cool effect, but professional lenses to do this can cost thousands of dollars. This Instructable tells you how to go about printing your own. For more info on the technique itself, check out this Wikipedia article.

New 3D Printer on the Block

If you would like to take the plunge into 3D printing, but are looking for somewhere to get a parts kit, the [ORD Bot Hadron 3D Printer] may be worth a look. The build quality looks great, and the price for the mechanical components is quite reasonable at $399. You’ll need to provide the electronics and extruder. Thanks [comptechgeek]!