Question: I am trying to recreate Wheatly from Portal, and I have tried to make his pixelated eyes by have a pixel grid with rectangular holes over the light source. However, as you can see by the picture, the curves within some of the pixels destroys the pixelated attempt. Is there a clear way for pixelating circuluar patterns like this? If, so, which method would you recommend? Thanks!
[![enter image description here](https://i.stack.imgur.com/wJjmW.png)](https://i.stack.imgur.com/wJjmW.png)

Answer: 
While I am not familiar with the subject in question, one way would be to use a custom image and use it as an emissive shader. 

image used: <http://orig14.deviantart.net/3961/f/2012/050/a/f/wheatley__s_eye_by_mycroftporthos-d4qarjf.png> 

Obviously you can find a better image (more pixelated) or make your own and use some filter in photo editors app like Photoshop, Affinity, Gimp or whichever you prefer.
Photoshop has a bunch of filter under the category Pixelate.
Affinity also has a filter under the Distort category called Pixelate and I'm sure Gimp also has one. 
[![enter image description here](https://i.stack.imgur.com/ldhYY.png)](https://i.stack.imgur.com/ldhYY.png)
This isn't more of an answer than [this one](https://blender.stackexchange.com/questions/112304/how-to-achieve-a-realistic-material-for-an-operative-phone-screen/118394#118394) by @Rich Sedman, but I've taken the 'pixellate' section from it and made an adjustable node-group from it.

This is the node group:

[![enter image description here](https://i.stack.imgur.com/MujpU.jpg)](https://i.stack.imgur.com/MujpU.jpg)

How it works is explained in the original answer.

This is an example of its usage:

[![enter image description here](https://i.stack.imgur.com/3bOTN.jpg)](https://i.stack.imgur.com/3bOTN.jpg)

Inputs: Number of tiles in X, Number of tiles in Y, The thickness of the borders between pixels as a fraction of 1 (the full UV dimension)

Outputs: The vector to plug into your image texture, and an 'In Border' value of 0 or 1, so you can decide what to do with the parts of the output between the tiles.

Example material: 

[![enter image description here](https://i.stack.imgur.com/Gsi5y.jpg)](https://i.stack.imgur.com/Gsi5y.jpg)

I can't promise it's bombproof .. or necessarily the simplest group to do this.

[![](https://blend-exchange.giantcowfilms.com/embedImage.png?bid=5478)](https://blend-exchange.giantcowfilms.com/b/5478/)