Question Help writing a shader that converts one color to another

I'm trying to write a shader that sort of acts as a lens that changes the color of whatever is behind it. So it would be transparent, but any pixels in a green range would be rendered as yellow, for example. I haven't had any luck getting this to work. Any help would be greatly appreciated!

 

You can use shader graph to create a screen space (post processing) shader that does this. Or you can create a shader in shader graph that samples the scene color (opaque texture) and do it that way!