I am wondering if there is a way to output a single image file that contains two layers: one with the rendered image, and one with the composited image.
This would be useful when importing renders in Photoshop, or in order to have two options for each image when exporting an animation. It could also be cool to have the composited layer and the rendered image when importing the sequence into an editing program (one would then have two footage layers instead of one and can blend/fade between the two etc).
Here's a file I experimented with, I exported to .tif which I think supports layers, but in Photoshop there was just one image.
