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Not every color camera has an IR filter, many phones and webcam lack such a filter and can see IR very well (on my phone it has a distinctive purple hue). Prob
by Valgrim 4y ago
Not every color camera has an IR filter, many phones and webcam lack such a filter and can see IR very well (on my phone it has a distinctive purple hue).
Probably this tint is compensated for in normal light.
- atahanacar 4y agoThat distinctive purple hue is a result of the IR filter. Filters on consumer cameras don't block 100% of IR, which is visible as that purple color. Useful for checking if remotes are working properly.
- dTal 4y agoI don't think it's because of the IR filter. I have removed filters from several color webcams and they always see IR as purpley. I think it's the bayer filter - the different color channels clearly have different sensitivities to IR.
- atahanacar 4y agoYeah, what I mean is the existence, the visibility of a slight purple hue. If the camera has no IR filter, you don't just see a slight purple hue on the LED itself, but you see the light just like you'd see a visible wavelength LED. I actually was obsessed with IR cameras and mods for some reason around 10-12 years ago. I remember using developed empty photo films to block visible light and let only IR through after removing the IR filter.
- starky 4y agoIf you look at a quantum efficiency chart you will find that CMOS sensors are actually sensitive to 850nm IR light almost identically at all photosites regardless of the colour filter and then they gradually decline together as the wavelength increases. The colour cast is mostly due to the tuning and white balance of the image.
- brk 4y agoBut phones and webcams don't really seem to be the target audience for this.