Hey, wasn't sure if this was a feature that I missed, but if not then consider this a humble idea/request.

If you've played around with Blueprints in Unreal Engine 4, you can double click node outputs to split them into component parts.    So in the context of Pixel Composer in particular, you could split the "Surface out" output of many nodes into various useful parameters like position, scale, opacity, etc. which could then be plugged into other nodes.

That's  a whale of a feature since it's very node-specific (or at least type-specific), so in the meantime you might be able to implement something similar by having a "get <parameter>" set of nodes for the more useful parameters. Say for example  if you wanted to get the position of a 2D    image node, you could input  a Surface and it'd output a Vector2.

Just some ideas.

Thanks for your suggestion! That's sure sound like a whale of a feature. I've never tried UE4 before so I might not understand it completely. But I think I can add a node that output properties of a surface like dimension like you've said. 

I'm not sure what do you mean by outputting position, opacity of a value tho. Can you explain more on that?