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I have a Raspberry Pi NoIR V2.1 camera. I am working with the NIR (940 nm) LEDs and I saw that I was getting funny/weird colors, so I assumed that it is due to the white balancing, so I switched off the auto white balancing (awb_mode = 'off') and set the gains to 1, 1 (awb_gains = 1, 1).

I believe my camera's white balancing is off now, however, I noticed that I am getting a weird split in the top half of the image. I noticed this phenomena in all images when awb is off and gains manually set to 1,1, while this does not appear when taking regular photos with white balancing on. Is there any explanation why is it happening? Has anyone encountered the same issue? Picture below shows output from the camera.

Image example

P.S. I checked with two NoIR V2.1 cameras that I have and both of them produce the same result, so it must be software based problem.

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I've not seen the splitting before but I have had some issues with gain settings.

  • Have you given the cameras 2-3s after initialisation to settle?
  • If yes, could it be the light is changing (flickering?) and the tearing is a result of the camera changing exposure mid-image? I think the data is captured as a stream the you 'read' a sensors worth.
  • This could be avoided by reading an exposure value and then fixing it. In python with picamera:

    cam.shutter_speed = 0   # Set to auto  
    time.sleep(3)           # Let the values settle  
    cam.shutter_speed = cam.exposure_speed     # Lock the exposure to the first auto value  
    
  • I was tripped over saturating one channel, this could be easily done with the infrared lighting?

  • What are the awb values set at with auto?

    • The docs say the awb values are 0-8, but if your lighting isn't even across the colours then you may want to boost the blue? (the image looks yellow so lots of red & green?)
  • I do give 2 seconds to settle after the camera initialization. It seems that I am getting this split constantly in the same spot - doesn't matter what the illumination is. The attached image above did not have any NIR lights on - just pointing the camera upwards. I checked all 3 channels and it doesn't seem that I am getting a lot of over saturation in any of the channels. Currently awb values are set as 1, 1. – Gytis Bernotas Mar 8 '17 at 12:12
  • hmm, that's a shame as it would have been an easy fix. What script do you use for image capture? – Craig Mar 8 '17 at 17:27
  • Did you ever get chance to try it with another light source? An incandescent bulb (or the sun) isn't going to flicker. – Craig Dec 6 '18 at 9:59

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