Seeing the Truly Invisible with DIY Shortwave UV Imaging

We’ve all seen how to peel IR filters off digital cameras so they can see a little better in the dark, but there’s so much more to this next project than that. How about being able to see things normally completely outside the visual spectrum, like hydrogen combustion or electrical discharges?

UV Electrical Discharge

[David Prutchi] has just shared his incredible work on making his own shortwave ultraviolet viewers for imaging entirely outside of the normal visible spectrum – in other words, seeing the truly invisible. The project has not only fascinating application examples, but provides detailed information about how to build two different imagers – complete with exact part numbers and sources.

UV-Viewer-SmallIf you’re thinking UV is a broad brush, you’re right. [David Prutchi] says he is most interested in Solar Blind UV (SBUV):

Solar radiation in the 240 nm to 280 nm range is completely absorbed by the ozone in the atmosphere and cannot reach Earth’s surface…

Without interference from background light, even very weak levels of UV are detectable. This allows ultraviolet-emitting phenomena (e.g. electrical discharges, hydrogen combustion, etc.) to be detectable in full daylight.

There is more to the process than simply slapping a UV filter onto a camera, but happily he addresses all the details and the information is also available as a PDF whitepaper. [David Prutchi] has been working with imaging for a long time, and with his sharing of detailed build plans and exact part numbers maybe others will get in on the fun. He’s also previously shared full build plans for a Raspberry Pi based multispectral imager, [David’s] DOLPHi Polarization Camera was a finalist in the 2015 Hackaday Prize, and he spoke at the Hackaday SuperConference about the usefulness of advanced imaging techniques for things like tissue analysis in medical procedures, and landmine detection for the purposes of cleaning up hazardous areas.

HDMI Extender Reverse Engineered

[danman] has been playing around with various HDMI video streaming options, and he’s hit on a great low-cost solution. A $40 “HDMI extender” turns out to actually be an HDMI-to-RTP converter under the hood.

He’d done work previously on a similar extender that turned out to use a quirky method to send the video, which he naturally reversed and made to do his bidding. But non-standard formats are a pain. So when he was given a newer version of the same device, and started peeking into the packets with Wireshark, he was pleasantly surprised to find that the output was just MPEG-encoded video over RTP. No hacking necessary.

Until now, streaming video over an IP network from an arbitrary HDMI output has been tricky, [danman] has been more than a little obsessed with getting it working on the cheap. In addition to the previous version of this extender, he also managed to get a stream out of a rooted Android set-top box. That costs a bit more, but can also record at the same time, should you need to.

None of this solves the HDMI HDCP encryption problem, though. You’re on your own for that one.

(Those of you Wireshark wizards out there will note that we just swiped the headline image from the previous version of the project. There were no good images for this one. Sorry about that.)

Hackaday Prize Entry: Adding HDMI to Small Displays

LCDs come in a lot of sizes, and there’s a lot written about pushing pixel data out to larger displays. Smaller LCDs, like the 4, 5 and 7 inch variety, aren’t used much, because no one seems to know how to drive the things. For [Joe]’s Hackaday Prize Entry, he’s creating an open source interface for tiny LCDs, making it easy and cheap to add one to everything with an HDMI port.

[Joe]’s Open LCD Interface comes on two boards, with the first providing connections to an LCD, all the power circuitry required, and a bunch of pads to break out every IO line. The second part of the puzzle is a decoder that takes HDMI signals and drives a small LCD.

HDMI decoders are nothing new to the world of hobby electronics – there are multiple projects that give the BeagleBoard a display through HDMI. Even Adafruit sells one of these converters. [Joe]’s board has another trick up its sleeve, though: it can give any microcontroller a high-resolution display, too.

There’s another module that connects to [Joe]’s breakout board that turns the LCD into an SPI display. This means any microcontroller can drive a high-resolution display. It’s fast, too: in the video below, [Joe]’s SPI display can push pixels at least as fast as any other microcontroller-based display we’ve seen.

It’s a great project, and a by opening up the doors to millions of cheap LCDs on eBay and Alibaba, [Joe] has a great entry for the Hackaday Prize on his hands.

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Using An FPGA To Generate Ambient Color From Video

We should all be familiar with TV ambient lighting systems such as Philips’ Ambilight, a ring of LED lights around the periphery of a TV that extend the colors at the edge of the screen to the surrounding lighting. [Shiva Rajagopal] was inspired by his tutor to look at the mechanics of generating a more accurate color representation from video frames, and produced a project using an FPGA to perform the task in real-time. It’s not an Ambilight clone, instead it is intended to produce as accurate a color representation as possible to give the impression of a TV being on for security purposes in an otherwise empty house.

The concern was that simply averaging the pixel color values would deliver a color, but would not necessarily deliver the same color that a human eye would perceive. He goes into detail about the difference between RGB and HSL color spaces, and arrives at an equation that gives an importance rating to each pixel taking into account its saturation and thus how much the human eye perceives it. As a result, he can derive his final overall color by looking at these important pixels rather than the too-dark or too-saturated pixels whose color the user’s eye will not register.

The whole project was produced on an Altera DE2-115 FPGA development and education board, and makes use of its NTSC and VGA decoding example code. All his code is available for your perusal in his appendices, and he’s produced a demo video shown here below the break.

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Where (Almost) No GoPro has Gone Before

What would it be like to ride a six foot rocket to nearly 400,000 feet at Mach 5.5? Thanks to UP Areospace and some GoPro cameras, you can find out.

The rocket was a test for the Maraia Capsule project. Mach 5.5, for reference, is 3,800MPH. It appears several different GoPro cameras took the footage. You can see the upward travel, some great views of Earth, and the return on the video below.

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Amazing Oscilloscope Graphics

From what we can understand, [ompuco] has built a 2D audio output on top of the Unity game engine, enabling him to output X and Y values from his stereo soundcard straight to an oscilloscope in XY mode. His code simply scans through all the vertexes in the scene and outputs the right voltages into the left and right audio streams. He’s using this to create some pretty incredible animations. Check out the video “additives” below for an example. (See if you can figure out what’s being “added”.)

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8-bit Video Wall Made From 160 Gaming Keyboards

Well this is something we haven’t seen before. A video wall An 8-bit style video wall made from 160 RGB illuminated gaming keyboards.

On display at the PAX East gaming expo, the keys on 160 Logitech keyboards make up the “pixels” of a video wall showing a short film inspired from side-scroller video games. It’s the work of the production company iam8bit. Details on the system are scant, but we can learn a little from close observation of the video.

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