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This is really cool -- pedantically, I've always thought "full spectrum" is actually misleading from a traditional photographic sense. Like IR + visible light + UV != full spectrum. I'd love to see post-processed imagery of every-day life through an extended view of broader EM energy (similar to astrophotography)... like what does a city scene look like with x-rays and microwaves included?

Side note: have always loved this image https://imgur.com/NZjWfWT of rainbows with UV and IR visible.

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Author here. I agree with you, "full spectrum" is a generous marketing phrase for what might more accurately be called _extended_ spectrum.

People way smarter than me have been able to achieve DIY spatial imaging with x-rays via compressed sensing [1] and with microwaves via phased arrays [2].

Optical wavelengths seem to be at a sweet spot of good angular resolution, varied natural sources, and harmless to humans.

[1] https://www.youtube.com/watch?v=EuVgGrun1V0

[2] https://www.youtube.com/watch?v=sXwDrcd1t-E

You'd obviously have to use false-color, as most modern astronomy pictures do (even the ones that use visible tend to pump the saturation UP!).

However, the amount of light from the sun drops off exponentially away from the peak at green-blue (yellow-green, after atmospheric filtering). You'd also have to really fake the dynamic range a lot to get it to look any different from IR+Vis+NUV. (If there was 0.001% as much x-ray light as there is, say, red light, DNA could only exist in the lightless depths of the ocean.)

So, it would look like an IR+Vis photo (light falls off pretty fast in the UV, too), except the ones you've seen oversell the IR.

So it would look like a Vis-light photo, with slightly shinier objects in it.

Sorry.

I like distinguishing "light" (physical world) from "color" (species-specific biology). Sunbeam blue light is already less intense than NIR-I, but human bio juices the blue. Most humans are bright-light trichromats and low-light monochromats. Rod sensitivity is 3 orders of magnitude up, with single-ish photon sensitivity. Some amphibians have an extra rod type, for low-light bichromaticity. Some deep-sea fish are bright mono and dark lotschromats (12+ rod opsins). So why not imagine seeing the world with a triple (or more) of short-wavelength super-rods, a few orders of magnitude more sensitive still, with whatever curves seem fun? Perhaps curves naturally selected for by "makes intriguing images of the world for social media"...

By this measure, there is no "full spectrum" photography ever.

If you specify the source used for lighting, e.g. solar light, you can define precisely what "full spectrum" photography is, i.e. recording a bandwidth large enough so that any lighting energy that falls outside that range is negligible.

Playing with a hyper-spectral imager makes you rethink how we see things. I've talked about this before, but human vision essentially "low resolution" on the spectral bands. Using an HSI that "sees" in 4nm spectral slices from 350-1000nm is really interesting (Cubert Ultris X20 Plus). There's so much spectral information that we just totally miss. I really wish the equipment for capturing images at these higher spectral resolutions wasn't so expensive so we could see people experimenting with them on a large scale. The one I got to work with was more than a nice SUV and that's cheap in the space. The ones we looked at from Headwall that did something like 400-2500nm started at $250k. Those weren't even full-frame imagers like the Ultris, they were line scanning imagers. That massive cost jump was down to the fact that from ~1050nm+ you need much different hardware to capture spectral data.

If anyone is interested in some technical aspects of the "full frame" HSI I worked with, it's quite interesting. It had a 20MP Monochromatic Sensor that captured single-band 12-bit data behind an array of lenses that split the incoming spectral range (350-100nm) into 164 individual 4nm wide bands of light that hit 410x410px squares on the sensor. The sensor can capture from 350-1100, but the QE drops of really fast past about 850nm and the product limited the upper range to 1000nm. I'm sure I munged something there, but you should get the general idea. I highly recommend researching the space of HSI, it's fascinating.

Last thing to point out, when working with an HSI like this, one thing you can do is capture a "spectral fingerprint". Since you've gone from three bands on spectral intensity information to, in our case, 164 bands you have the ability to turn that high-density spectral data for each pixel into essentially a line graph. Using that information you can do matching against a database of known spectral fingerprints and identify materials and material properties really well. In the multi-spectra world you'll see this capability used to identify crop health. In the hyperspectral world you can identify so much more. For instance, it can see skin anomalies that aren't visible to the human eye. You can identify specific minerals in a picture of a bunch of rocks (you need up into the 2500nm range for this though). You can easily spot foreign objects on a conveyor of food items. Overall, it's a long list of capabilities and I'm certain there are many more uses we could discover if the imagers were cheaper. And if you are into the wider ML world (not just focused on LLMs I mean), you'll see ML Classification Models being trained on these spectral fingerprints as well.

Anyway, the "full-spectrum" is fascinating, especially when you are able to slice it thin.