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Why is my video blurry for 5 seconds?

  1. Nov 1, 2016 #1
    I have a video to present to my class and for five seconds it goes all blurry.
    Does anyone know how to sort it out and why it happened?
  2. jcsd
  3. Nov 1, 2016 #2


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    Staff: Mentor

    Because something is wrong.

    Sorry, amount of details you gave doesn't guarantee a better answer. There are tens of formats, thousands of codecs, hundredss of programs you could use to make the video and to show it. Every combination has it quirks, and you want us to guess where is the problem just like that?
  4. Nov 1, 2016 #3


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    Staff: Mentor

    A common cause could be the auto-focus feature on your camera/phone. Is there a way you can disable it so it won't get confused during your "filming"?
  5. Nov 1, 2016 #4
    A normal bridge camera was used and it kept on going out of focus which isn't very helpful. And the camera isn't mine and I can't re-film it.
    It is in mp4 format and I haven't converted it.
    Sorry about the brief previous question, I was in a rush (I always am)
  6. Nov 1, 2016 #5


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    Science Advisor
    Gold Member
    2017 Award

    ....... which is also very unhelpful ... what is a normal bridge camera ?

    to get decent help, you need to start posing your questions much better and give lots more information
    else all of us here are just playing the frustrating "20 questions" game

  7. Nov 1, 2016 #6
    If it is blurry, there's not much that can be done about it without a very big effort.

    With the path of least effort you may need to modify the levels in a video editing software. It will give a clearer image to the human eye, but the blur will still be there since you are just modifying the color channels. It is called Image Correction by Level Adjustment. In case you want to look for it :wink:.
  8. Nov 2, 2016 #7
    Let me expand and add a little.

    There are different kind of blurs. Let's assume that the kind of "out-of-focus" blur that you got can be approximated with a Gaussian blur, the most common kind of blur. To artificially create that gaussian blur, you convolve an image with some kernel. This means that you would need a deconvolution algorithm which needs values (varying by function) to deconvolve. Because you don't have the values, you would need to approximate by trial and error. That can easily prove to be a hard task.

    In any case, if you don't feel like programming it yourself, you can look for deconvolution software used in image/video forensic analyses. Those are your keywords. :smile:
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