In photography and cinematography, a multiple exposure is the superimposition of two or more exposures to create a single image, and double exposure has a corresponding meaning in respect of two images. The exposure values may or may not be identical to each other.

Digital technology enables images to be superimposed over each other to create the effect above.  Known as double exposure, the user can adjust the opacity and blending mode of the images to create a image that uses positive and negative space and value to form its subject. Many digital SLR cameras allow multiple exposures to be made on the same image within the camera without the need for any external software.

How do we do it?

First we take two photographs. The first is our subject. We want to isolate them against a solid background like the sky. 


Our second photo will be of a pattern, tree, bush, building, or something with rough irregular edges.   


In photoshop combined the pictures. I changed the blending mode to use Linear Dodge (additive) on the tree image. 


Next I select the sky in Layer 1 add a layer mask to the duplicated background layer. Then I create a new layer and fill it with white. I place this new layer under my duplicated background.


To finish, I add two adjustment layers. A black and white and a strong contrast curves adjustment. 


Here is my final image after posing my subject slightly different.