In this Photoshop tutorial, we’re going to use Image Stacks to remove people walking through a scene. This technique does require some planning and the use of multiple photos, but the results are amazing!
The Image Stack Mode method is perfect for removing people from crowded places or unwanted objects that are moving through a scene.
The Image Stack Mode will take a statistical average of the content found in all the photos. It will keep identical areas and remove everything that changes between the different shots.
It is very likely that cars and people will move and change locations. Thus they will be removed when the algorithm is applied, leaving only the background.
When you’re out taking the photos make sure that your camera is on a tripod so that the images line up better during the blend. If you do not have a tripod, make sure that you hold your camera as steady as possible when shooting your images.
Wait 20 seconds or so in between each shot. You want to give people and cars time to move. In most cases, you will only need between 8 to 20 photos.
In this tutorial, we’re going to use nine photos that I shot with my cell phone without using a tripod.
For this video, I wanted to use photos that were not shot under the perfect conditions so that you could see the power of this technique.
Steps to completing this tutorial:
Load Multiple Files as Layers
The first step is to bring those files into Photoshop as layers. To do so, go to File > Scrips > Load Files into Stack…
In the “Load Layers” window select “Folder” from the “Use” dropdown. Then click on the “Browse” button, and look for the folder containing your images. If you are following along with my images, find the folder titled “stacking.”
Press OK after you have selected the folder.
The file names will appear within the window. If all the files are there, press the OK button to move the files into Photoshop.
For the Image Stack to work, these layers need to align. If you used a tripod when shooting the images, then your layers should already be aligned.
The photos used in this tutorial were not shot with a tripod, so they will need to be aligned in Photoshop.
To align the layers select them all by pressing Command Option A (PC: Ctrl Alt A).
Then go to the Edit menu and select “Auto-Align Layers.” Make sure that “Auto” is selected, and press “OK.”
Photoshop will then look through all your layers to find similar pixels and align them together.
Put The Aligned Images into Smart Object
Select all your layers again, and right click on the side of any selected layers and choose “Convert to Smart Object.”
Apply The Median Stack Mode To The Smart Object
Now that all the layers are inside a Smart Object we can control how the set blends by using a “Stack Mode.” Go to Layer > Smart Objects > Stack Mode > Median.
This Stack Mode takes a statistical average of the content found in all the photos. It keeps identical areas and removes everything that changes between the different shots.
In other words, Photoshop will eliminate any object that is not constant through all or most layers, such as people walking through the scene.
Faster Way of Doing This! Statistics Script
You can get to this point in the tutorial by simply using one command.
Go to File > Scripts > Statistic.
In the Image Statistics window, select Folder as the Use, and click on the Browse button to find the images that you want to use in the Image Stack.
Once the images load, select Median as the Stack Mode, and check “Attempt to Automatically Align Source Images.”
This command will Auto-Align the images, put them in a Smart Object using the Median Stack Mode. Getting you to this part of the tutorial.
Note: A Smart Object is a container that can hold one or more layers. It allows you to apply editable adjustments, distortions, filters, and transformations.
Fixing Image Stack Errors
Problems may arise when dealing with background elements that are constantly moving, such as water or flags.
In this example, the two flags on top of the Tribune Tower disappear. We can bring them back by copying and pasting a flag from one of the original images.
To do this, go to Layer > Smart Object > Edit Contents.
A new tab will open up that contains the contents of the Smart Object.
Then go to the layers labeled “02.jpg” this image, in my opinion, contains the best version of both flags.
Select the Lasso and make a selection around the American flag. With the selection active press Command C (PC: Ctrl C) to copy.
Go back to the working document and paste the flag there. Command Shift V (PC: Ctrl Shift V). Repeat these steps with the smaller flag below the American flag.
Crop The Image
Use the crop tool to crop the picture. Press C on the keyboard, then use the handles to adjust the size of the crop. Press Return when you’re done.