[Using a greyscale image as a 'filter' for an image in a layer below]

Hello, I have an effect that I want to try to do.

 

I have an image whose colors I like, but the shading and contrast I don't. I have a black and white version of that same image, where I've gotten the contract where I want it.

 

I don't know how to explain this in computer graphics terms, so bear with me:

 

What I would like to do is have an effect where I put the black and white image on a top layer, and have it 'filter' the image below it. What I mean is that, if a pixel is white in the top layer, it becomes transparent and the pixel below is shown. If the pixel is 50% grey, I want it to be 50% transparent. If it's black, it's opaque.

 

Is there a way I can do this in paint.net natively, or with a plugin?

[Image subtraction?]

Can I do an image subtraction in Paint.NET? It's where you take two images, and if the colors are the same at any pixel, it's made transparent, so that only the differences remain.