View Full Version : Brightness and Contrast controls

March 13, 2004, 03:54:05
This is more of a frame grabber question, but one I hope someone here can answer. I am trying to understand exactly what changing the BRIGHTNESS, CONTRAST properties do. For example, I would think that these parameters affect the A/D converter's dynamic range used for digitization, and maybe the reference offset used as well. Can anyone confirm that?

I was also wondering if someone could give some suggestions for how to set these values automatically. For example, we are using the ImagingSource firewire framegrabber, and we have a procedure where we cover the camera to get a "dark current" reading (sample of frames). The average of these dark current frames are then subtracted from the image frames in order to reduce the background noise level at the expense of dynamic range. We can enhance the dynamic range by setting the BRIGHTNESS and CONTRAST controls to minimize the perceived noise levels coming back from the frame grabber when there is essentially "dark frame" coming from the camera. I was hoping someone could validate some of those ideas, or give me a pointer as to where I can find more information.