(H) Ed Halley's

GIMP Tutorials

Using Multiple Exposures in Photography

The following is a brief tutorial on how you can take and edit multiple distinct digital photographs taken from a single vantage point for creative photo-manipulated effects. This includes separate scanned film images, or separate images from a digital camera.

Removing Transient Objects

Sometimes people or cars or animals or airplanes or other moving objects just get in the way of the perfect photograph. Well, not when you can merely edit them away!

If you can make objects translucent, you can make objects disappear almost as easily. You just need a little patience and a tripod, and you can empty out that crowd of people who are walking through your "studio." The more transient objects you must remove, the more photographs you'll need to get that clear shot.

As with the previous examples, I've taken multiple pictures from a single tripod-equipped vantage point. I then combine them all as one XCF-format file in the GIMP, each image as their own layer. The first screenshot below demonstrates the photographs I merged using the same technique explained earlier.

combining many layers

erasing cars in each layer

patching potholes

In the GIMP's Layers dialog, as mentioned earlier, you can show or hide each individual layer by clicking on the eyeball icon that is next to the layer's thumbnail.

Hide all of the layers, and you will see a checkerboard pattern which the GIMP uses to indicate that nothing is visible.

Now show just one layer photograph. Choose the Eraser tool with a nice large-sized brush, as shown in the second screenshot above. Erase those pesky unwanted objects, leaving transparent holes in the layer. Wherever you erase in one layer, that checkerboard pattern (or other layers) will show through.

Repeat the process for each layer. You can show two layers at once, to show how the erased objects allow new patches of the preferred scenery to become visible instead. Keep revisiting each layer, removing every unwanted object carefully. Erase sparingly, but thoroughly. If you preview the way the layers interact occasionally, you may find you don't even need to erase every object in the lower layers, because the desired scenery blocks it out in higher layers.

There are two potential problems you may face in a complex erasure like the one in this example. One, you may have parts of the scene which was not empty in any of your photographs. Two, you may have accidentally erased too much of the desired scenery along with the unwanted objects, leaving a hole through all of your layers. In most cases, one solution will solve both problems: patching or cloning.

In the third screenshot, there was one tiny spot in the distance where none of my available layers showed empty road. Each layer had some portion of a car visible. I carefully selected a small patch of empty roadway from the next lane, and copied and pasted that patch to the offending spot on the road.

In this case, I was lucky. I was careful to match the coloring of the roadway at the problem area, and could easily repair one small hole in the background of the picture. If there was some mismatch in color, I could also try using the Airbrush or Smudge tools to blend in any troublesome lines.

This cut-and-paste repair technique could also be used to remove a few ugly pieces of litter which appeared in every shot, but that's an exercise that I leave to you as you try your own projects.

Next Section: Overlaying Transient Objects

Contact Ed Halley by email at ed@halley.cc.
Text and artwork are Copyright © 1996-2005 Ed Halley
Copying in whole or in part, with author attribution, is expressly allowed.