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Colour planes still existing after filtering

  1. Jan 22, 2014 #1
    Hey. Im wondering how can blue and green colour planes exist in a photo, when im using red bandpass filter while taking photos? Red bandpass filter lets only red light through. But when i analyze the photo, green and blue planes are still there. How can it be?

    Thanks in advance
  2. jcsd
  3. Jan 22, 2014 #2


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    What do you mean with "still there"?
    Filters and color-sensitive detectors are not perfect (and they would not work as intended if they would be perfect) - even with a filter, you'll get non-zero green and blue values in a digital image.
  4. Jan 22, 2014 #3

    Andy Resnick

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    If I understand your question, its because the light passing through the filter can still be (barely) detected by the green and blue sensor pixels- the Beyer filters are fairly broad, do you have any specs on your red filter?
  5. Jan 24, 2014 #4

    Claude Bile

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    I agree with Andy - the blue and green sensors will still register a response when exposed to red light because the spectral response curve partially overlaps the red part of the visible spectrum.

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