Separating Shadows In A Render

Hi Blender community,

I have a render in which I need to render the shadow separately. By this, I mean the shadows on the object itself not the cast shadows. I think I will be using a combination of render passes to achieve this result.

The reason I need this is to be able to modify (increase or decrease the intensity of the shadow) the shadows layer in photoshop during post-processing.

I have tried to use the shadow render pass but it seems to only render a black and white image of where the shadows are, so very light soft shadows are rendered completely black.

Any help would be much appreciated, thank you.