Adobe added an artificial intelligence-powered air substitute to Photoshop in late 2020. You can quickly and easily replace the sky in any photo with another. It̵
This tutorial is split in two a bit. First, we’ll discuss the actual operation of the tool, then take a look at some of the problems you may encounter when creating credible images. Sky swapping is nothing new for photographers, but the automated Photoshop tool makes it a lot more accessible for beginners and faster for experts. Let’s dig in!
How to use Photoshop’s Sky Replacement Tool
To start, open the photo you want to edit in Photoshop. We use the photo above of a lighthouse. The sky in the picture looks okay, but it could use some bumping.
Clicking Edit> Air Replacement will take you to the Air Replacement utility. Most of the heavy lifting is done by Adobe’s AI / machine learning algorithms (called Sensei), but there are a few more options here to break down.
To select a sky, click the preview image of the sky and then click one of the options. The tool comes with about 25 standard skies in three categories: “Blue Skies”, “Spectacular” and “Sunsets”.
They are all pretty decent. However, keep in mind that these are the default skies built into Photoshop, so they will become very popular.
A better option is to go with your own heaven. To do that, click on “Create New Sky” at the bottom right. Navigate to a photo you took (or found on a site like Unsplash) with a dramatic sky, then click ‘Open’. The sky you select will immediately appear in your image.
Adjust the air replacement
The rest of the options in the Sky Replacement tool are for tweaking things to make the overall picture look natural. On the left you will see the following tools:
- Sky Move Tool (Shortcut V): This works just like the normal move tool. You can click and drag the sky to move it on your photo. In the images above, the sky I selected added a mysterious island to the background, so I’m going to use the move tool to get rid of it.
- Tool Sky Brush (shortcut B): This one is a bit different from the regular brush. This allows you to paint over any area and tell Photoshop that you want to add more of the new sky to the image. You can also hold down Alt (Option on a Mac) and paint to tell Photoshop to remove some of the new sky. You don’t have fine control, but it is useful to correct any small mistakes the AI makes.
- Hand (Hotkey H) and Zoom Tools (Hotkey Z): These are just like the regular tools. You can click and drag the hand to move through your image or click the zoom tool to zoom in. Hold down Alt or Option, then click to zoom out.
There are additional sliders, check boxes, and drop-down menus, including:
- Shift Edge: Moves the boundary between the new sky and the foreground. Negative numbers add more foreground, while positive numbers add more sky.
- “Fade Edge”: Blurs and blurs the line between the new sky and the foreground. Use a higher number if the transition is more blurred and a lower number if it is more defined.
- “Air Adjustments”: The “Brightness” slider makes the new sky darker or lighter, while the “Temperature” slider changes the white balance. The “Scale” slider changes the size of the background image and the “Flip” check box rotates it around its horizontal axis.
- “Foreground Adjustments”: “Lighting Mode” gives you the choice between “Multiply” (the sky will darken the foreground where they overlap) and “Screen” (the sky will light up the foreground where they overlap). “Lighting Adjustment” adjusts the amount of lightening or darkening. “Color Adjustment” defines the power of Photoshop’s AI-powered foreground recoloring based on the new sky.
- “Export”: Here you can “Output to New Layers” (the better choice), which creates separate layers for all effects. If you select “Output to Duplicate Layer”, it merges everything into a single flat layer.
- “Preview”: Selecting this check box enables or disables the preview of the image. It is wonderful to see how your new heaven compares to the old one.
The only way to really get a feel for the sliders and options is to play with them and see how they affect the sky in your image. When you are satisfied with everything, click ‘OK’.
The pitfalls of air replacements
Technically, air replacement in Photoshop is now very simple. You just open an image, play with a few sliders, and boom! New air.
Below are the before and after versions of our image.
Even if you zoom in super close, you will see that Photoshop does very well. In our image below, the glass through the center of the lighthouse looks a bit off, and some of the wires and one of the birds are gone, but we’re looking for problems. You can usually view the edited image without horror.
However, the same cannot be said for every image. Below is another photo of the same lighthouse. Can you spot the problem?
How about this shot of another lighthouse? The problem is a little easier to spot here.
How about the image below? It’s actually from Adobe, and it has some serious flaws.
Have you seen them all? This is what we found:
- In the first image, the old sky is still reflected in the smooth water.
- In the second image, the sky is just way too exaggerated for the foreground. No amount of machine learning can solve that.
- In the third image, the sun’s position is much lower and shifted to the left. This means that the dramatic lighting on the surfer and his board conflicts with the direction of the light.
Here’s an even worse example from that last song.
The colors actually fit quite well here, despite how dramatic the sky is. However, the sun is clearly on the left, while the shadows and highlights on the woman and her dog come from a sun rising somewhere to the right.
It’s great that the Sky Replacement tool is so quick and easy to use. However, that also means you can use it without giving it a long thought. There are a lot of potential pitfalls in replacing much of an image, especially if you want it to look realistic.
And realism is important. Most people will notice that something is not quite right with an image if the direction of the light is wrong or if the colors do not match. They may not be able to explain it exactly why things are out, but they will know.
How to get Sky replacement right
The golden rule of air replacement is that the more the air you exchange resembles the air you exchange, the better. Instead of looking for a ridiculously dramatic sky, try to find something similar to the one in the picture, only better.
The two most important things to look for are light direction and color. If the light direction is different, you can’t do anything in Photoshop to make up for it. No amount of playing with sliders can change the direction of the shadows in the foreground. So start with a sky with a similar light direction and use the Move tool and the Scale and Flip options to align it.
Colors are a little easier to fix because if you have Photoshop skills you can tweak them quite a bit. Yet there is a limit. If you have a very high-contrast, saturated foreground, go for a high-contrast, saturated, dramatic sky. If the foreground is a bit more muted, a sky that is also subdued will work better.
Also, light has different colors at different times of the day. If your image is from the blue hours of the eve, a golden sunset just looks wrong. The more the sky and foreground colors look alike at first, the better the finished image will look.
The best thing about Photoshop’s sky replacement tool is that as long as you select “Output to New Layers”, all automated edits are added as editable layers and masks. This means you can edit things afterwards with manual tools and use the full power of Photoshop on your image.
Like pretty much everything else, the only way to get good at photography and Photoshop is practice. It’s cool that replacing a sky in Photoshop is no longer a technical challenge, but a creative one. So make sure to try different things. Push your images too far and, if it all looks wrong, try to figure out why.