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Redrobes
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raspistill -t option and colour

Sun Aug 03, 2014 5:19 pm

Hi, I have a couple of cameras on pi's and I have a small identical problem with all of them. I wondered if anyone could point me at the documentation for why its happening, confirm that other people see it, or maybe post an explanation.

The issue is that if I run the cameras with raspistill and use the -t option with 1000 then its ok. If I run it with -t 0 or -t 500 or something less than 1000 then the colour seems to be very red - at least its not at all correct and nothing like what it is if I run -t 1000+.

Specifically the issue is with something like this:
raspistill -t 500 -o image.jpg

no issue with
raspistill -t 1000 -o image.jpg

The documentation I am looking at doesn't specify that it has a minimum value.
Anyone know whats going on or confirm that its an issue ?

gordon77
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Re: raspistill -t option and colour

Sun Aug 03, 2014 5:48 pm

I think its a feature rather than an issue, you need time for the camera to settle,

Here's an old quote by jamesh

» Mon Oct 28, 2013 10:56 am

-t 10 is very very short - should be 0 or probably at least 750.

gordon77

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Redrobes
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Re: raspistill -t option and colour

Mon Aug 04, 2014 11:51 am

Thanks Gordon. It sounds like this is known behavior and that there is such as thing as too short and ill just assume that its necessary to have some delay before the camera is ready. Maybe the documentation or the --help should reflect that the CCD needs time to stabilize and that 750 or 1000 is a minimum required value. I mistakenly thought it was just a feature to allow for some timed shutter delay rather than a hardware boot up fix.

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RaTTuS
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Re: raspistill -t option and colour

Mon Aug 04, 2014 11:54 am

-t, --timeout : Time (in ms) before takes picture and shuts down (if not specified, set to 5s)
from the help but ... yea should be documented
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AndrewS
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Re: raspistill -t option and colour

Mon Aug 04, 2014 12:01 pm

Trouble is, I believe the "settle time" (while the camera auto-adjusts its white-balance, gains, etc.) depends on the brightness of the scene? So the "minimum time" value will change :?
http://picamera.readthedocs.org/en/rele ... -to-a-file simply recommends always waiting two seconds.

gordon77
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Re: raspistill -t option and colour

Mon Aug 04, 2014 12:12 pm

I run my camera with the -tl 0 and -t 0 options and it produces images in approx 700mS, so that seems adequate.

gordon77

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