Announcement

Collapse
No announcement yet.

Removing moire patterns fro line-cut images

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • Removing moire patterns fro line-cut images

    I am experiencing some problematic patterns with some line-cut images. I arrived at this site while searching for an FFT filter (new to me).

    Please see the PDF and original images as an example.

    Thanks for any assistance.
    You do not have permission to view this gallery.
    This gallery has 2 photos.

  • #2
    This has been a problem since the beginning of digital photography. It's becoming less so with higher-resolution imaging tech. But scanners are pretty much stuck at the same resolution they have been for a decade. Moiré is caused by the interference pattern between the image data and the size/number of photo receptors. Solving it requires changing one or both of these.

    FFT only works for regular, repeating patterns. Moiré is very irregular.

    Some techniques that have proven to work (sometimes) in the past:

    Scanning off-axis (at an angle). This could require combining good parts of scans done at different angles.
    Taking a photo instead of scanning. This is probably the most successful technique. Some modern cameras have effectively more resolution than the best flatbed. Conversely, if these are from a camera, try a flatbed scanner. You're basically looking for the highest DPI imager you have available.

    Anyone else, feel free to post your own tips and advice here.
    Learn by teaching
    Take responsibility for learning

    Comment


    • #3
      This might help a little



      Scan_RemoveMoiréPattern 09-2010 cc
      REMOVE MOIRÉ PATTERNS FROM SCANS
      Moiré patterns can occur when scanning photos from printed matter
      such as books. They are crosshatched or dotted patterns resulting
      from interference between the printed image and the scanner. This
      does not occur with original photographs and slides.

      Some moiré can be prevented during the scan by using the
      “descreen” option. If this does not work or was not done, moiré
      patterns can be reduced in PhotoShop:
      1. Scan the image at a resolution one to two times higher than what you need
      2. Open the scanned image in PhotoShop
      3. Set view to 100% magnification
      4. Go to Filter > Blur > Gaussian blur. This may be sufficient for some images
      depending on the type of moiré pattern.
      5. Go to Filter > Noise > Median - use a radius between one and three. The higher the
      quality of the source, the lower the radius can be used. One often works for books,
      two for magazines, and three for newspapers.
      6. Go to Image > Image Size > reduce to the desired image size and resolution
      7. Go to Filter > Sharpen > Unsharp Mask – begin with settings of:
      Amount: 50 – 100%
      Radius: 1
      Threshold: 1
      Depending upon the image resolution, these settings may need to be adjusted. Use
      the Preview Window to determine the best settings for a particular image.
      8. If you see glowing or a halo effect in the image after using the Unsharp Mask, go to
      Edit > Fade Unsharp Mask > set Opacity to 50% and Mode to luminosity > click OK.
      9. Save your changes when satisfied with the results. If not satisfied, changes can be
      undone at any time in the History Tool or by using Edit > Undo.




      Comment

      Related Topics

      Collapse

      • Isedo
        Removing Moire from scanned images
        by Isedo
        Hi, I'm looking for some def technique to get rid of that moire effect in scanned images. How do you solve this kind of problems?

        Suppose to have 10 images to work ok, which is the better way to preserve the sharpnes on them and get rid of the moire?
        All filters do some kinda of...
        07-07-2009, 04:02 AM
      • jstar
        Removing "pattern" from the photo
        by jstar
        I started restoring my family photos.

        I am currently restoring pictures from the photo album around 70s.

        In the photo album, the dust cover (plastic) has made certain patterns to the images.

        Please see an attachment to see it.

        This pattern...
        09-09-2007, 04:56 PM
      • BethT
        Help, please with removing "dots"
        by BethT
        Client brought this in...poor quality reproduction of original (which is gone). I've done my best, but can't remove the dotted pattern. Suggestions are most welcome!...
        07-07-2009, 04:02 PM
      • Navstar
        Removing paper embossing
        by Navstar
        This is just a portion of an image I'm trying to restore. Unfortunately, it's printed on this crazy textured paper.

        I've read about FFT plug-ins here. Is there any FFT plug-ins on the Mac side? If not, I have a friend who has PC CS3. Does FFT work on grayscale images?

        Here's...
        08-18-2008, 12:16 PM
      • Habanero
        FFT making transparent images
        by Habanero
        Hi everyone! Photo restoration is a hobby of mine, so I'm happy I found this place. I've been restoring some old photos of a family friend and thought to try the FFT filter on the harsh texture of the paper. Come to find out FFT only works on patterned texture, not frog skin texture. It's kind of charming...
        09-11-2011, 06:28 PM
      Working...
      X