Create an object that has the basic shape of your pixels and assign 3 materials to it:

[![enter image description here][1]][1]

[![enter image description here][2]][2]

For each of the materials use the image texture and a split RGB mode to control the brightness of the emitter material. Here's the setup for the red material:

[![enter image description here][3]][3]


Note that I'm using an empty to control the texture coordinates.

Then by creating arrays of your base object, and controlling the size and placement of your texture using the empty you can get what you are after:

[![enter image description here][4]][4]


  [1]: https://i.sstatic.net/vHVC0.png
  [2]: https://i.sstatic.net/Drqn2.png
  [3]: https://i.sstatic.net/kPl0E.png
  [4]: https://i.sstatic.net/aWB44.jpg