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22226RE: [SeattleRobotics] Low light cameras?

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  • Jay Beavers
    Feb 1, 2005
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      I've had very good experience with the Logitech QuickCam 3000 & 4000 and low
      light conditions both for robotics and more traditional digital video
      capture. The Logitech consistently outperformed much more expensive, high
      end cameras (AKA the Sony Firewire series and a few others) for dealing with
      low lux, even those with adjustable irises.

      The Logitech cameras add most of their low lux capability from post
      processing the image in the driver. I've been told by someone who's a
      specialist in image processing that Logitech uses the "it's a grey world"
      algorithm that assumes that a picture should be balanced out to an "expected
      ratio" of grayscale. This might not work so well for the "shooting against
      a background of white" scenario mentioned at the start of the thread.

      We've been very pleased with the ability of the Logitech to pick out an
      orange code in indoor and outdoor environments in a variety of lux
      conditions. My wife had to spend some time tuning our software to figure
      out what the range of RGB values are that correspond to "orange" under
      different lighting conditions. The ironic thing is that if you take the
      center numbers of the RGB ranges she came up with and write that color to
      the screen it looks grey to a human eye. However this approach seems to
      work very well for positive detection of orange without false detections, so
      it must be something about the YUV components of "orange" that is more
      detectable to a computer.

      - jcb

      -----Original Message-----
      From: Alan King [mailto:alan@...]
      Sent: Monday, January 31, 2005 4:29 PM
      To: SeattleRobotics@yahoogroups.com
      Subject: Re: [SeattleRobotics] Low light cameras?


      Jay Prince wrote:

      > Webcams are generally intended for indoor shooting, and should be
      > better for low light situations....
      >
      >

      Other way around, you're indoors at a computer at a generally fixed
      distance
      so they expect decent lighting not less, even good webcams are actually
      terrible
      at low light for the reasons given. And without post processing from the
      Windows driver they're even worse. The CMUcam basically is a webcam, if
      they
      were much good at low light it'd already be working..


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