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Faults: screening

For an in-depth discussion of print screening, see http://en.wikipedia.org/wiki/Halftone .

Most print media is screened, which appears in scans as a dotted pattern. This must be filtered out after scanning.

Examples of traditional screening. Click the image to compare the raw and descreened image.

FM screening (also known as stochastic screening) is a newer, higher-definition printing process. FM screening still requires descreening to reduce noise, but is much simpler to process. Examples:

Improper filtering can lead to moire effects.

For more information on how to remove screening from scans, see: forum #2007, forum #2290.
Updated by fireattack over 2 years ago