i'm using the camera module of the raspberry pi v2 , it's pi NoIR


the problem is that the black color appeared as a purple and other colors are also different using it on day , i don't know what is the problem or if i could change some settings to make colors appears more original

Any hints ?


This is typical for a PiNoIR camera (or any camera with the IR filter removed): black appears as purple because although it's black to your eyes, the camera's still seeing a fair amount of red (from near IR, invisible to humans), and a little of blue (from near UV, which IR filters aka hot mirrors also filter).

Here's a nice graph of CCD sensitivity, and hot mirror response which should explain the phenomenon far better than I ever could in text:

enter image description here

So, your regular Pi camera (or any old CCD with an IR filter) will have a response curve limited by the cyan (hot mirror) line in that graph. However, the PiNoIR (or any old CCD without an IR filter) will have a response curve limited by the black line.

If you want it to look "normal" you need to stick an IR filter over it (or get a camera with an IR filter installed in it).

  • thanks , so it would be much better to use a regular camera for photography .... , for me i am using the camera for face detection : can you tell me if there is a difference between using the pi noIR or the the regular camera for this purpose – The Beast Aug 25 '15 at 23:38
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    If the algorithm you're using doesn't depend on color (and as far at I'm aware most of them don't), then it shouldn't matter - the luminance is probably similar enough that it should work normally. – Dave Jones Aug 26 '15 at 5:02
  • yes you're right it use haar classifiers wish had nothing to do with luminance , thnaks – The Beast Aug 26 '15 at 9:14

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