Photoshop CS3's Automatic People Remover.
Two weeks ago we ran a tip on how to remove unwanted people from public photos. Apparently, it's a popular topic — that post received almost 20,000 visitors in the first 10 days. Less than a week after publishing that tip, I ran across another technique using Photoshop CS3 Extended that makes the process virtually automatic.
As before, you must take several shots of the same scene using a tripod. This technique uses a new feature in Photoshop CS3 Extended called image stacks. With the right settings, Photoshop automatically identifies areas that are similar between your photos (the unchanging background) and removes the elements that change between shots (the wandering people).
So, if erasing people by hand seems like too much work to bother with (and if you spent the extra money to get the Extended version of Photoshop CS3), you can use this cool automatic people remover technique.
Step 1: Take multiple photos with a tripod.
To demonstrate this technique I visited the Fremont Troll who lives beneath a bridge in Seattle's Fremont neighborhood. This whimsical public art attracts the procession of visitors and tourists we needed in order to demonstrate this people remover technique.
While only three photos are shown here, we actually shot about 6 photos over a couple minutes.
Step 2: Load your photos into an image stack.
In Photoshop CS3 Extended, choose File > Scripts > Statistics.
Pick the collection of photos you took with a tripod. Go ahead and check the "Attempt to Automatically Align Source Images" checkbox for good measure.
And the magic option: Choose a Stack Mode of Median.
Note: This script is not available in the standard version of Photoshop CS3 — you must be using the Extended version.
The Results: People Automatically Removed!
Photoshop will process for a few minutes as the images are loaded, and after a moment you'll see your resulting image with most of the people automatically removed. Cool!
How does this work?
This technique exploits a new feature in Photoshop CS3 Extended called an image stack. Look in your Layers palette, and you'll see that your images have been converted into a special type of Smart Object. That icon we've circled in our screenshot indicates that your layer is an image stack.
An image stack creates a single composite view out of a larger collection of images (in this case your original photos shot with a tripod). By choosing different stack modes (Layer > Smart Objects > Stack Mode) you can change how Photoshop generates that composite view.
Using the median setting, Photoshop automatically identifies areas that are similar between your photos (the unchanging background) and removes the elements that change between shots (the wandering people).
Experiment with the other settings and see what types of results you can achieve.
Source: This tip inspired by a timely episode of the fun Creative Sweet TV podcast. For another great example of this technique in action check out the always entertaining Russell Brown with his video tip: Smart Objects and Stack Mode Settings - The Disappearing Cars!