I came across this image of an artist on a website. I was wondering what this type of effect on images was called and how I can post process my photos get this effect?
For a free program that will convert any image to a multi sheet half tone image see comment at end.
This appears to have been "screened" possibly with a physical screen layer but more probably in an image editor.
The effect is a variant of "half toning".
From above, the "old way" is:
With CS3 and above
Excellent wikipedia discussion which goes into the historical background and gives a good feel of the uses which are made of this effect - usually with much lower dot sizes. View this image from a distance such that the dots are not able to be individually resolved:
Expansion - Right eye (left as we view it).
Half toning is used to produce an apparent grey scale image in processes that can only produce on/off 2 level monochrome - such as newspaper printing presses.
From Wikipedia (above ref)
Rasterbator - Free half tone conversion program. - excellent.
The Rasterbator is a free raster conversion program which outputs a half tone version of an input image. The user can control number of sheets in output image. dot size and a bit more. Version 1.21? available here
Use too large a max dot size compared to selected total image size and you can get "modern art" with no obvious relationship to the original. Ask me how I know :-).
This allegedly supplies a link to an online version but I get "permission denied".
The main effect is called "halftoning".
You can get to it in the GIMP using Filters→Distorts→Newsprint. In most other image editors, it's available through the Filter or Effects menu, and is usually labeled "Halftone". In Photoshop, for instance, it's "Filter→Sketch→Halftone Pattern...". In PaintShop Photo Pro, it's "Effects→Artistic Effects→Halftone...".