ofVideoGrabber + Unibrain Fire-I color banding / posterization problem

Hi,

I’m having this problem:

I’m using a Unibrain Fire-I 530b firewire camera to do detection of people in a space. The camera is fitted with an IR pass filter.

When I access the camera with ofVideoGrabber I get this horrible color banding / posterization effect that is unusable for my tracking system: (see attached image)

I have tried to use QTkit ( with ofxQTKitVideoGrabber ) to access the camera image, and I get a very good quality image but I can’t access the camera settings for using manual exposure / gain / framerate etc…
Of course I need these manual settings for good detection, so that is not an option unfortunately.
The second attached image shows the quality with ofxQTKitVideoGrabber.

Does anyone know why I get this posterizing / color banding effect only with the ofVideoGrabber?

I’m on OSX 10.6.8, OF0062

thanks for any clues to this mystery,
tim.

![](http://forum.openframeworks.cc/uploads/default/1937/Screen shot 2011-11-04 at 14.41.13.png)

![](http://forum.openframeworks.cc/uploads/default/1938/Screen shot 2011-11-04 at 15.06.12.png)

no idea why you get the banding, surely is some weirdness with quicktime. For firewire cameras it’s actually better to use ofxVideoGrabber or ofxLibDC

Hey Arturo,

Thanks for the super quick help! much appreciated.
I had never heard of ofxLibdc… oops!

I’m trying it right now and it looks good.
Now I’m working on a version that will play nice with 0062 and get those frame rate / exposure / … settings to show up…

I’ll keep you posted.

best,
tim.

Thanks again Arturo, your suggestion worked perfectly.

best,
tim.