Moiré Avoidance


Cliff Hall
 

Dan,
Thank you for digging these up, they will be a great help to me.  In my other hobby of genealogy I run across halftoned images quite a bit so this knowledge will be quite useful.
Cliff 


Dan Margulis
 

A few weeks ago there was a brief thread on proper angling to avoid moiré patterns, usually but not always because we are scanning a prescreened original. Not all the advice there was accurate.

This is understandable because documenting the techniques is quite difficult. Most of the time when the moiré is apparent in print, it is not visible on a modern digital proof. Nor is it readily detectable on a monitor. You could have seen it on a Cromalin or Matchprint of the previous century, but those were very expensive, out of the reach of books and smaller magazines, So anybody who wrote about it had to be pretty confident that a certain file that looked OK on the screen and the proof would create moiré when ink hit paper.

This limited the field considerably, and as a result my two 1997 columns on the topic are still AFAIK the authoritative source. Unfortunately, they've never (until now) been posted, because the source files I have are useless to show what happens on press.

In cleaning out my office I found the original magazines, and scanned them. These do show where moiré is occurring and I recommend that those interested in the topic give them a look. Here are the links to the two 1997 columns:
A New Angle on Descreening Art
Mathematics, Moiré, and the Artist

They are now part of an archive of my columns, which contains writings on a number of topics of interest to this group.

Dan