10/03/2013

Remove Moire Pattern from Scanned Image

Photographs scanned from books, magazines and newspapers or photographs from TV screen or projected images often results in an unsightly interference pattern called moire. This is how to remove the effect in Photoshop.
  1. Go to Filter > Noise > Median.
  2. Use a radius between 1-3. Typically the higher the quality of the source, the lower the radius can be. Use your own judgement, but you will probably find that 3 works well for newspapers, 2 for magazines, and 1 for books.
  3. Go to Image > Image Size  and resample to the desired image size and resolution using the bicubic resampling option.
  4. Make sure you are zoomed to 100% magnification.
  5. Go to Filter > Sharpen > Unsharp Mask.
  6. Exact settings will depend on the image resolution, but these settings are a good starting point: Amount 50-100%, Radius 1-3 pixels, Threshold 1-5. Use your eye as the final judge.

Tips:

  1. If you still see a pattern after applying the Median filter, try a slight gaussian blur before resampling. Apply just enough blur to reduce the pattern.
  2. If you notice halos or glows in the image after using Unsharp Mask, go to Edit > Fade. Use settings: 50% Opacity, Mode Luminosity.

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