There is an effect that I want to be able to recreate - bonus points if I can turn it into an action or a script. Basically, I want to be able to change a shape into a set of diamonds, and I want it to vary in size, as in the attached image.
How can I recreate this effect in Adobe Illustrator or Adobe Photoshop?
It's a halftone pattern. Some hints how to get it:
Get Inkscape. It's free. There you can tile any shape (including your 45 degrees rotated square) with the "tile clones" function. It has an option to modulate the sizes of the tiled shapes with the local brightness levels of the underlying image. The result is the wanted halftone pattern and it's vector. The shapes are perfectly sharp.
Here's an attempt to apply Edit > Clone > Create Tiled Clones to a screen capture of your color image:
Without the underlying image it's this:
The original shape (which in the pattern will present solid black) is in the top left corner.
Parameter gamma is essential if one wants to find the best presentation of the features in the original photo. It probably is better to adjust the photo in GIMP or Photoshop to have a good scale of greys. An example:
The gamma shift in the tiling dialog is zero, but the photo itself has been edited as shown.
Even heavier edit to the original may bring some details more visible, but substantial improvement needs smaller dots. An example:
The photo has got a local contrast boost and the dot size is reduced about 50%.
ADD: A comment (by Billy Kerr) shows a version https://i.sstatic.net/TtCRnQJj.png where the image is edited so much that the background and a large part of the face have became white.
He is right - it's more like your example. I skipped it because I didn't want to present a version where all information is lost in some face areas.
Another route:
Raster image editors have half-tone effects. If you have high enough image resolution you can make something resembling, but that's a raster image. The resulted dots look easily too rough if the resolution is not high enough.
Photoshop's Bitmap image mode is perhaps the simplest way to get the effect in a raster image editor. But the effect looks rough:
The used bitmap mode variation is "halftone screen, diamond". The shapes generally are distorted badly except in areas where the brightness is about 50% of the maximum.
