Removing Moiré Patterns from Magazine and Newspaper Scans

By Dan DiNicolo, April 20th, 2007 Posted in Scanning. Subscribe to our RSS Feed

Unlike a traditional photograph, images and text found in magazines and newspapers are printed using a half-tone pattern. While this is not generally discernable to the human eye under normal reading conditions, look closely enough (perhaps with a magnifying glass) and you’ll notice that the image is actually made up of a dot-like or crosshatch pattern. Unfortunately, this pattern is most evident when you scan either of the above as a traditional colour or grayscale photograph, and seriously compromises the quality of the scan. To the uninitiated, this “effect” is commonly referred to as a moiré pattern.
The great news is that why moiré patterns represent a rather serious obstacle, most scanning software includes a simple and effective filter to tackle the problem. Known as a descreen filter, this is often implemented as a simple checkbox or drop-down menu option in the advanced settings of the scanning software. Depending on your scanning software, it may also include an option to scan from a magazine, which will implement the descreen filter automatically. While scanning an image using the descreen option will take considerably longer than without, the results speak for themselves, as shown below. Note that the descreen filter is not necessary (or useful) when scanning traditional photographs, since these do not suffer from the same moiré pattern issue.

Written by Dan DiNicolo - Visit Website

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