The technique allows the photographer to produce ghost images and mirror images that tell a story in a unique way.
This effect can be achieved with a DSLR camera by enabling Multiple Exposure in the shooting menu, but for more creative control, you can replicate the effect using Adobe Photoshop or GIMP with your own images or stock photos.
As early as 1890, the double exposure was being used as a finely tuned technique. The origin of the work entitled “The Ghost of Bernadette Soubirous” is unclear. But this image, which depicts the saint, dressed all in white, seemingly vanishing through a wall, was a very deliberate use of multiple exposures.
Try to think of a good message to convey. All you really need are two images, so take your time in figuring out what you want them to be.
Some of the most compelling double exposure images are composed of a portrait and an abstract or landscape photo with a lot of interesting textures. Create a connection between the two to produce an image that evokes certain emotions and makes your viewers take a few more seconds to observe the photo and contemplate the underlying message.
Your base photo can be anything—a portrait, body part, still object, or even a popular scenic spot—as long as it has a main subject, a good amount of highlights and shadows, and a background that is more or less neutral without noisy image elements so that it’s easier to edit later on.
For a much cleaner double exposure image, you can try placing your subject inside your frame completely until you can see its outline pretty well. The resulting image will give you something like the image above, where the double exposure image is created with the shape of the tree.
Your layer photo can also feature anything from an overhead shot of the city to a grassy yard or forest. Remember to evenly expose your layer image. For example, if you’ve decided on taking a photo of leaves on a mango tree, look for a good spot that is not too bright and not too dark. This way, you get an image that has a good amount of highlights and shadows that would look more visible once blended with your base photo.
Once you’ve chosen your best base and layer photos, open both files in Photoshop, Pixlr, Photopea, etc.
Touch Up Your Base Photo
Move your subject to center it or off-center to follow the Rule of Thirds, depending on your desired final composition. Tweak the brightness and add contrast in order to optimize the image for blending.
Go to Image > Adjustments > Levels or press Ctrl-L to open the Levels menu. Move the white slider to the left to brighten the image and then move the left black slider to the right to add some contrast according your taste. Or, you can set numerical values: 7 for black, 1.15 for greys, and 197 for whites.
Eliminate the Background
Use the Quick Selection Tool or Magic Wand Tool to select the entire background area and any other image element that you wish to get rid of, and then go to Select > Inverse to invert the selection (now your main subject).
While still on the selection tool, use the Refine Edge Tool, tick the Smart Radius box and slightly increase the Radius value in the Edge Detection to 1.5 (or higher for frizzier outlines) to reveal minor details like hair strands.
In the Output section, select New Layer with Layer Mask in the Output To options window. This creates a copy of your image and hides the background without making permanent changes to your image file.
Finally, click on Add a Mask and then Create a New Layer. Move this new layer underneath the cut-out subject and fill it with white or a neutral color (like light medium gray) using the Paint Bucket Tool.
Add the Layer Image
Drag the second image on top of the first image (previously edited main subject). With the second image selected, press the Ctrl key and click the Layer Clipping Mask button of the first image (main subject) layer below. You will then see the moving outline of the main subject’s silhouette on the landscape layer. Unlink the mask and move or rotate the second photo until your desired part is within the outlined silhouette.
Blend the Images Together
Experiment with the layer blending options -- for the second image, try using the Screen layer, which should offer a good amount of transparency to reveal the second photo underneath.
Add a Final Top Layer
Finally, make a copy of the subject layer, drag it on top of the second layer, and change the subject layer’s blending mode to Lighten. Go ahead and make your finishing touches, such as softly erasing the topmost subject layer to show more of the landscape layer underneath.