How about something like this?

![Dot matrix example][1]

Workflow:

 1. Identify the nearest hole.
 2. Find the distance to the hole.
 3. If the distance is greater than the radius, use transparent. Otherwise, use the central color of the center of the hole.

Blendfile: [link](https://www.dropbox.com/s/0g0qossrgw5gzia/DotMatrix.blend).

**Main node setup** (right-click → *Open Image in New Tab* to see larger):

![Main node group, "DotMatrix"][2]


  [1]: https://i.sstatic.net/Xw2mj.png
  [2]: https://i.sstatic.net/7LmB9.png