Looks like oversized halftones to me...
Check the tutorial I posted a day or two ago in this section, set the value to a higher number to achieve bigger dots
Here's the link:
Halftones for Inkjets (no RIP needed) TUTORIAL
Here's a quick pic to achieve the same result:

<--- Click to enlarge
This also works with gradients as well, to have the dots go from larger to smaller