Digital Video Noise Reduction

Discussion in 'DVD' started by ScottR, Aug 27, 2003.

  1. ScottR

    ScottR Cinematographer

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    Can someone explain to me what this looks like? I watched an episode of Charlie's Angels and it looked like what I think DVNR is. For example, in a scene with lots of lights, the lights in the frame bounce all over the place. When you pause the picture, the lights (for example, shining on the side of a glass or other objects) alternate between light and dark, causing the picture to "dance." Would this be something that was done in the digital realm, or is it caused by NTSC lacing or inherent in the original print? Thanks for your comments.
     
  2. Jeff Kleist

    Jeff Kleist Executive Producer

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    No, that's not DVNR. The best way to explain what DVNR is is to do this

    Take a pencil and lightly shade a section of the page, now take your finger, and smudge it until you no longer have individual lines but a basically solid grey area. That's basically what DVNR does, sacrifice detail for uniformity and grain reduction. If you have the new Animal House disc, compare the laundromat scene in the new documentary (where are they now) to the one in the actual movie. That's an extreme example mind you, the smearing is pretty bad there, and probably the source of Landis' desire to "degrade" the transfer
     
  3. ScottR

    ScottR Cinematographer

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    So this was probably a problem inherent in the print? None of the other episodes look "overprocessed" like this. You can even see leaves on the trees "changing" in every frame to the point of distraction, like one part of the frame is moving while the rest is not.
     
  4. Damin J Toell

    Damin J Toell Producer

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  5. Patrick McCart

    Patrick McCart Lead Actor

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    DVNR is an electronic processor that automatically smooths out film scars such as specks, dirt, scratches, etc. However, it's easy for it to be overdone.

    A good (or bad) example of over DVNR-ing a video transfer can be found in most of Artisan's Republic releases. The detail is very faint and it has an odd "smoothed" look to it.
     
  6. Jeff Kleist

    Jeff Kleist Executive Producer

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    The documentary carrys the DVNR'd to death footage
     
  7. Robert Dunnill

    Robert Dunnill Second Unit

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    Here's a good page on DNR (found it through IMDB).
     
  8. DaViD Boulet

    DaViD Boulet Lead Actor

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    DNR can produce "flickering" and "shifting" that look very MPEGy. This happens when the film frame weaves/bobbs slightly and the DNR algorithm has trouble "locking" onto the image...it can't quite tell if the changing picture information is noise or not while the image shifts position.

    This is a BIG PROBLEM with "backgrounds" where there is a pattern like grass, leaves, or wall-paper. Just when the DNR "locks" and gives you a clear picture of the detail the frame moves just a hair and everything goes blurry or gets "crawlie" until the DNR can "lock" again. Ugh...it looks aweful. Last Days of Disco has this problem BIG TIME.

    Also often noticable in the skin-details of actor-closeups. When the faces stand still you get a clear view...then the actor barely moves and all the facial detail in the skin goes blurry or gets "noisey" with a wierd digital grain until the actor stops moving.

    -dave
     

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