Results 1 to 6 of 6

Thread: Gaussian blur/heavy blurring and banding issues

  1. #1
    Forum Participant
    Join Date
    Jan 2008
    Location
    Leiden, The Netherlands
    Posts
    1,020
    Threads
    148
    Thank You Posts

    Default Gaussian blur/heavy blurring and banding issues

    Dear all,

    The last weeks I have been experimenting with more agressive ways to blur the BG of pictures where the BG is distracting (due to noise or contrast issues involving white and black spots in the BG) and doesn't add to the overall environmental feel of the photo. I tried using Gaussian blur/Lens blur/several runs of noise reduction and more than once this has resulted in mild to severe banding issues in the BG.

    1. Does anybody know why this is a problem in some photo's while in others it is not?

    2. Does anybody know how to solve this apart from not bluring the BG of course?

    It is really frustrating because some photo's IMHO are ideal to be saved in this way.

    I hope you can help!

    Cheers,

    Krijn
    Last edited by Krijn Trimbos; 08-07-2009 at 09:28 AM.

  2. #2
    Super Moderator arash_hazeghi's Avatar
    Join Date
    Oct 2008
    Location
    San Francisco, California, United States
    Posts
    18,545
    Threads
    1,318
    Thank You Posts

    Default

    Can you post an example?

  3. #3
    Forum Participant
    Join Date
    Jan 2008
    Location
    Canada
    Posts
    6,588
    Threads
    643
    Thank You Posts

    Default

    I remember a thread about this a while ago but can't find the link. Essentially the gist is that if you apply heavy-handed blurring to reduce noise in an area of an image with little detail that you get banding. Apparently a certain amount of random noise is important to give you smooth total gradations, but I can't remember the physics behind it.

    You can try it yourself- make an image with some noise in the sky for example, then run over the sky repeatedly with the blur brush in Ps set to 100%. You will begin to see banding.

  4. #4
    Fabs Forns
    Guest

    Default

    And if you work in 8 bit, it may be worse.

  5. #5
    Banned
    Join Date
    Feb 2008
    Location
    Colorado
    Posts
    3,949
    Threads
    254
    Thank You Posts

    Default

    Quote Originally Posted by John Chardine View Post
    I remember a thread about this a while ago but can't find the link. Essentially the gist is that if you apply heavy-handed blurring to reduce noise in an area of an image with little detail that you get banding. Apparently a certain amount of random noise is important to give you smooth total gradations, but I can't remember the physics behind it.

    You can try it yourself- make an image with some noise in the sky for example, then run over the sky repeatedly with the blur brush in Ps set to 100%. You will begin to see banding.
    Hmmm... I can see how this could happen if your strokes were back and forth, but if you use more random motions it should not produce banding. Like try circular strokes. Or select a region then feather/refine edge and the run a blur filter and I have never seen it produce banding. Can someone post a before and after example?

    Roger

  6. #6
    Fabs Forns
    Guest

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Web Analytics