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I'm currently designing a poster, and when I view the design in Illustrator my Ben-Day dotted images are heavily distorted in their color and spatial appearance.

I really like this. Is there a way I could (possibly in Photoshop) recreate these distortions so they end up in my exported pdf?

This is how the poster looks when exported to png:

enter image description here

Here's a screen-shot from Illustrator:

Screen-Shot

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Nothing like finding a style by accident! –  SaturnsEye Apr 3 at 10:38
    
I recommend looking up "The Theory of the Moiré Phenomenon" by Isaac Amidror if you'd like a more in depth look on the subject. It's very math-heavy, but the basic ideas are presented very clearly. –  Alex Blackwood Apr 3 at 19:58
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up vote 7 down vote accepted

If we look how the Moiré pattern is created we can see that it is the result of rotating linear patterns:

enter image description here
Soure: Wikimedia

This is mostly unwanted on fast method scaling of images that have a regular pattern, or on displaying such images on a display made up of regular patterns too (like our screens).

To intentionally produce this effect we need a source image dithered with a regular pattern such as the halftone dithering of the example given.

Below are steps to transform an image with adding Moiré:

  1. Dither source image using a regular pattern:

    enter image description here

  2. Copy the image and paste it as a layer on top of the dithered source

  3. Apply a rotation to the pasted layer (the angle will control the effect size)

    enter image description here
    Moiré overlay with transparency

    enter image description here
    Moiré overlay with 50% opacity

    enter image description here
    Moiré overlay with a line-dithered source

From examples above we can see that the primary dithering technique will deptermine the shape of our Moiré (diamonds produce diamonds and lines will produce lines).

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how do you make the line-dithered halftone? –  Bakabaka Apr 3 at 13:21
    
@Bakabaka Actually I made it using a GIMP Distort > Newsprint filter. No PS here, so I could not say what its name is (but I am pretty confident you have such a filter in PS too). –  Takkat Apr 3 at 13:26
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I don't know if there is a filter per se, but at the very least, one can take each channel and convert them to greyscale then bitmap and then back to greyscale and then paste them back into the channel. give each the appropriate line-screen angle for the channel in the bitmap step. –  horatio Apr 3 at 15:31
    
@horatio: appears the way to go in PS - as far as I could find out you can only generate halftone patterns including line on separated color layers. –  Takkat Apr 3 at 17:29
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