[Question] USB-Web-Cam becomes slower as darker the image becomes

[Question] USB-Web-Cam becomes slower as darker the image becomes

[aldoric]

Hello,

I'm new to v4l-development. I was able to get the raw image into my application successfully. But the current problem is not only in limited to my self-developed application.

All of my USB-webcams will get less FPS as darker the image becomes. In optimal cases I get around 30 frames per second. But if it's really dark I only get around 2-3 FPS.

I think that it might be the software gamma-correction. On v4l2ucp I didn't find a way to disable it.

What do you think is the way to fasten up the video-recording? How can I disable software gamma-correction if this is the reason?

Thanks in advance


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Re: [Question] USB-Web-Cam becomes slower as darker the image becomes

[Michael Riepe]

Hi!

aldoric@gmx.de wrote:
> Hello,
> 
> I'm new to v4l-development. I was able to get the raw image into my application successfully. But the current problem is not only in limited to my self-developed application.
> 
> All of my USB-webcams will get less FPS as darker the image becomes. In optimal cases I get around 30 frames per second. But if it's really dark I only get around 2-3 FPS.

I suppose the camera (or the driver) is increasing the exposure time to
compensate for the lack of light and/or reduce noise.

> I think that it might be the software gamma-correction. On v4l2ucp I didn't find a way to disable it.

I don't think that will help. But you may try to turn off auto-exposure.

-- 
Michael "Tired" Riepe <michael.riepe@googlemail.com>
X-Tired: Each morning I get up I die a little