I am capturing images using raspistill on a NoIR camera. Every now and again images under "reasonable" (indoor) lighting seem to go pink for just one or a few frames. I assume this is some kind of issue with the AWB, so I have tried setting this to off, and also using --stats which is supposed to calculate white balance from the captured image rather than heuristics. For some reason it appears to be approximately the same "amount" pink whenever it happens as well, but that could just be my eyes.
Here is the line for my raspistill capture - it's in a bash loop, with $2 being the shutter speed, chosen elsewhere in the script, so I get roughly consistent exposure levels over time (hence forcing the -ev -24 and ISO 100 as well):
raspistill -set -ss $2 -vf -hf -ev -24 -ISO 100 -awb off -awbg 1.0,1.0 -drc high --stats -n -q 10 -t 100 -w 648 -h 486 -o /dev/shm/img.jpg
Attached are also two shots taken of exactly the same scene, seconds apart and with the same exposure, showing the effect. The room lighting is tungsten/halogen lamps, so it can't be anything to do with e.g. 50Hz flicker of fluorescent or LED lighting or similar.
I have not noticed anything similar on my normal (non-NoIR) camera, so I'm wondering if this is something screwy with the white-balance algorithm on IR images?