LED pixel Lights for Vray

Hi Everyone,

I want to create LED light material in certain patterns and color backgrounds.
This image is a reference. I want all sizes of dots to light up in one color while choosing my own background color, and making it into a vray material that I can apply to any object.
Is there any way that I can use emissive material and cover up the back of the dots so it lights up the dots only? (this is what my imagination is going toward) Thank you!