Tag: Moiré

With frequency-modulated screening (non-periodic screening), the halftone dots are distributed pseudo-randomly. Different tonal values result from the varying number of dots of the same size on one surface.
FM screening produces better colour gradients and avoids Moiré effects.
Especially finer details can be displayed better with an FM screen than with an AM screen.

The Moiré effect or, in other words, a halftone overlay, is a common phenomenon when viewing prints. It occurs when two even patterns overlap unevenly.

When does Moiré appear?

Moiré always occurs when screens overlap. Typical examples:

• You have scanned in a newspaper ad and print it in another newspaper.
• You print the portrait of a managing director wearing a jacket with a fine houndstooth pattern, a checkered shirt and a finely patterned tie. Regardless of the printing process, complete Moiré chaos is guaranteed to break out here.
• A brick building is reproduced in offset printing.
• The photograph of a ventilation grille is viewed on a monitor

You can find further information here:
What is Moiré? And can I see Moiré in a proof?