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gfd | 3 years ago

I remember my old android phone would pick up IR as a purpleish color: https://qph.cf2.quoracdn.net/main-qimg-d8d68a82c1ec4b4975b8e...

I wonder if it's possible to make it bright enough to blind regular (non IR filtered) cameras too?

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tjkrusinski|3 years ago

No, older smart phone cameras lacked IR filters because the IR filter didn't only block IR light, but also a distribution of wavelengths around IR. Filtering out IR means many of the visible light wavelengths are attenuated as well, decreasing the amount of light arriving at the sensor.

With better noise reduction algorithms, more sensitive sensors and lower noise sensors, IR filters are now almost always used in smart phone cameras.

jandrese|3 years ago

Also, without an IR filter those cameras could partially see through light clothing in bright conditions. This of course formed a creepy online community and enough backlash that the manufacturers decided to include IR filters for all future products.

SnooSux|3 years ago

I work with IR sensors at work and modern smartphones pick up NIR frequencies as well. It's picked up by the red channel so combining that with the blue is probably what's making the purple color.

My guess would be that something bright enough to wash out the red channel would still leave the blue and green intact. So there should be enough information that the image is degraded but not necessarily blinded.

But I could be wrong, depending on how independently the color sensors and processing work.