palavrov
Posts: 33
Joined: Wed Jul 11, 2018 12:11 pm

Some camera settings doesn't work.

Fri Oct 12, 2018 7:53 am

Hi,

We hit another problem and need support - @6by9 could you take a look to this please?

Taking two images from the camera with different ISO settings results in more or less the same picture i.e. we were expecting to easily visually differentiate ISO 100 from ISO 200 for example.

Here is a demo project that shows the problem.
https://github.com/palavrov/camera-app

And here are two pictures taken with it:

ISO 100: https://pasteboard.co/HI4OvN5b.jpg
ISO 200: https://pasteboard.co/HI4P2ei.jpg

Changing white balance red/blue gains was not working too, may be it is related?

6by9
Raspberry Pi Engineer & Forum Moderator
Raspberry Pi Engineer & Forum Moderator
Posts: 5684
Joined: Wed Dec 04, 2013 11:27 am
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Re: Some camera settings doesn't work.

Fri Oct 12, 2018 10:08 am

palavrov wrote:
Fri Oct 12, 2018 7:53 am
We hit another problem and need support - @6by9 could you take a look to this please?
Trying to tag people using @username does not work on phpBB.
palavrov wrote:Taking two images from the camera with different ISO settings results in more or less the same picture i.e. we were expecting to easily visually differentiate ISO 100 from ISO 200 for example.
Why/how are you expecting to see a difference seeing as you haven't fixed the shutter speed / exposure time. AGC/AE are still aiming for the same target brightness in the scene, therefore your cranking the gain up x2 by setting ISO200 just means it will turn the exposure time down to half the value. No net resulting difference to the images except for possibly some extra noise.
If you were capturing via the stills port the EXIF data would have shown you that. You can read back OMX_IndexConfigCameraSettings to get the current gains and exposure settings.
palavrov wrote:Changing white balance red/blue gains was not working too, may be it is related?
Nope. Almost certainly you haven't set the white balance mode to OMX_WhiteBalControlOff via OMX_IndexConfigCommonWhiteBalance, therefore the automatic algorithm is still running.
Software Engineer at Raspberry Pi Trading. Views expressed are still personal views.
Please don't send PMs asking for support - use the forum.
I'm not interested in doing contracts for bespoke functionality - please don't ask.

palavrov
Posts: 33
Joined: Wed Jul 11, 2018 12:11 pm

Re: Some camera settings doesn't work.

Fri Oct 12, 2018 12:43 pm

6by9 wrote:
Fri Oct 12, 2018 10:08 am
Why/how are you expecting to see a difference seeing as you haven't fixed the shutter speed / exposure time.
I think that fixed them i.e. for OMX_IndexConfigCommonExposureValue:

bAutoShutterSpeed is set to OMX_FALSE
nShutterSpeedMsec is set to 50000

bAutoSensitivity is set to OMX_FALSE
nSensitivity is set with the ISO value we want - 100, 200 ...

Isn't that the way to fix them?

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