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Thread: How to know if captured frame is valid

  1. #1
    Join Date
    Oct 2003
    Location
    Atlanta, GA. USA
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    56
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    9

    How to know if captured frame is valid

    I am using the continuous capture mode on the Imaging Source FireWire framegrabber to capture a stream of frames. Sometimes I notice that when I start the capture, the first one to three frames or so show the blue background with "NO VIDEO", and then I get the frames from the camera as expected.

    Is there a way to know that I am getting "good" frames from the camera?

  2. #2
    Join Date
    Jan 2003
    Location
    Bremen, Germany
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    4,864
    Hello,

    At this point of time, there is flag to indicate, whether a frame is ready or not.
    I use for testing whether a frame is valid, the colors of the first few pixels. If they all are blue (RGB 0,0,255) (if you set an RGB video format), then it is improbable that the frame is valid. If you convert from a YUV format, the value for blue differs from the blue value of an RGB video format. This depends on the YUV->RGB transform filter.
    If the frame is valid, it is very improbable that a few pixels in one line show the same blue color values because of the normal noise of the camera.
    Best regards
    Stefan
    IC Imaging Control Support

  3. #3
    Join Date
    Oct 2003
    Location
    Atlanta, GA. USA
    Age
    56
    Posts
    9
    OK, that's the approach I am taking as well. Thanks for the info!

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