Matched using perceptual hash algorithms that have an accuracy between 20% and 40%.
Inductor
There's a smaller version of type F that has the same frame as type N, just missing the middle pin, so it is reversible. It has the same risk of reversing neutral and phase as type F, but (while I'm no expert) that has never been a problem for me.
It's missing the European high voltage plugs as well.
It is open source, licensed under the Apache License 2.0.
EDIT: Found it on f-droid: https://f-droid.org/en/packages/app.organicmaps/
base12 has the advantage of being divisible by 2, 3, 4 and 6, while base10 is only divisible by 2 and 5.
Optical Character Recognition. Basically just extracting text from an image.
You can do this in VLC, though it's not very practical. VLC's equalizer has a preamp slider, it's just not great if you want to change it all the time.
Here's a circular rainbow from ~~an aircraft~~ a skydiver:
EDIT: image embedding didn't work
EDIT 2: not from a plane
EDIT 3: sorry for all the edits, fixed image
I'm not an expert, but I guess it would depend on the speed of sound in the rod.
Unfourtunately, I couldn't find a source stating it would be required. AFAIK it's been assumed that they would use perceptual hashes, since that's what various companies have been suggesting/presenting. Like Apple's NeuralHash, which was reverse engineered. It's also the only somewhat practical solution, since exact matches would be easily be circumvented by changing one pixel or mirroring the image.
Patrick Breyer's page on Chat Control has a lot of general information about the EU's proposal.