There’s nothing to see here, move along. It’s a quick and dirty execution of a simple post processing (PP) technique. Before starting this project I couldn’t imagine a use for it. After finishing, one idea popped. More about that at the bottom.
Few digital cameras allow in-camera multiple exposures, that is, stacking images to create a combined whole. There’s little reason to, as it can be easily done in PP. Here is the easiest way.
1. Underexpose a backlit subject against a simple background. The sky makes both a good backdrop and a great light source. Here is the railing on my balcony, shot from ground level. See those shadows? They’re about to become a blank canvas.
2. Find something to fill the shadows in #1. One can harmonize with the dark shape, find a counter point, get whimsical or just be F’ing lazy and shoot whatever is nearby. This is the floor of my balcony.
3. PP Mumbo Jumbo: Create a luminosity mask to select the shadows. Select that shape from the pattern in #2 and combine with the Photo in #1.
Now do you see why I advised you to move along?
4. One can also combine the texture of the shadows with an opaque version of the pattern.
Now I want to combine a backlit statue with a flock of pigeons landing. First I need to find a statue of someone other than a King or a religious leader.