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Details of color video vs monochrome

  1. Dec 6, 2018 at 1:45 AM #1
    I have a cctv camera that is defective that only gives violet image. I think the IR filter mechanism is broken and it is out of warrantee.

    I'd like to know how poorer can you resolve details using monochrome than using color. So I can decide whether to replace it (won't if the details are the same or close).

    Thank you.
     
  2. jcsd
  3. Dec 6, 2018 at 3:02 AM #2
    The missing/broken IR filter just makes it sensitive to near IR, it won't make the image violet. More likely one of the color channels is broken: the sensor or the following electronics.

    Originally monochrome image could be more detailed than colored one due the video signal coding (and some other factors), but that was before the whole image sensor business fired up. Right now it's not possible to say anything without knowing the exact components of the camera.

    Knock it a few times and if it does not start working normally, just replace the thing.
     
  4. Dec 6, 2018 at 3:36 AM #3
    How do images look with missing/broken IR filter?
     
  5. Dec 6, 2018 at 3:44 AM #4
    With one word: weird.

    Ps.: these are photos, not CCTV, but the point can be seen I think: the picture is definitely NOT violet.
     
  6. Dec 6, 2018 at 3:58 AM #5
    It's bluish, see the thumbnail. It's not the IR filter?
     

    Attached Files:

  7. Dec 6, 2018 at 4:37 AM #6
    Here is another clue. At night time with artificial lighting, the color becomes normal. I really think it's the IR filter. At daytime, the whole image is bluish.
     
  8. Dec 6, 2018 at 6:35 AM #7

    jedishrfu

    Staff: Mentor

  9. Dec 7, 2018 at 1:53 AM #8

    Tom.G

    User Avatar
    Science Advisor

    Here are the color histograms of the posted image. As you can see, the Blue channel is almost completely saturated. It looks more like a display problem than a camera problem, but it could be either. It may be a Blue channel gain adjustment that is faulty or has a bad solder joint. If you consider the camaera no good the way it is, open it up and see what you can find. Often, but not always, manufacturers will take the trouble to label things on the circuit boards. If you open the camera, do your best to keep dust off of the image sensor. A small dust speck will look like a boulder in the image!
    upload_2018-12-6_23-44-41.png

    Cheers,
    Tom
     
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