1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

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


    User Avatar
    2017 Award

    Staff: Mentor

    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

    User Avatar
    Science Advisor
    Education Advisor

    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

    User Avatar
    Science Advisor

    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.

Share this great discussion with others via Reddit, Google+, Twitter, or Facebook