Picture this if you will: you’re out in nature with your hopes, dreams, and a camera to capture it all. You see the beauty of creation stretching out before you, so you carefully and patiently set up your gear to get the perfect shot. Finally, the sun moves to just the right spot, and you hold your breath while you press the shutter button. Then you realize the clouds are all wrong. You can wait for hours for the ideal opportunity to present itself, or you can do sky replacement using Photoshop to drop in another one. It’s not as difficult as it might seem and can lead to some exciting results.
Before you get started with this operation, you will need two pictures: one with a boring sky and one with a breathtaking sky. If you’re just getting started, I recommend using two pictures shot at a similar time of day under similar conditions. If you replace a sunny sky with storm clouds, the lighting will be all different, and the results will look, well, Photoshopped.
After finding a picture with a nice foreground, you need to get another picture with an interesting sky.
The plethora of screenshots below might seem overwhelming, but this entire process is quite easy and a lot less complicated than it seems. Fire up Photoshop, follow along carefully, and you should have some good results in no time at all.
Step 1: Get rid of the boring sky
Open your picture with the sky you want to replace in Photoshop. If you’re not familiar with Photoshop, you’ll see that the Layers panel on the right side has your picture as the Background layer. It’s locked, meaning you need to unlock it or make a copy. Go with the latter route by right-clicking and selecting Duplicate Layer.
Click the new layer in the Layers panel to make sure it’s actually selected. You will know it’s selected by the outline that you can see around each corner of the layer thumbnail.
Click the eye button next to the original Background layer to make it invisible. It’s still there if you need it for any reason, but if all goes well, you should be able to do the rest of this entire process using the duplicated layer.
The next thing you need to do is remove the sky, which you can do with a technique known as layer masks. Start by clicking the Selection tool and holding it down until the pop-up menu appears. Click “Quick Selection Tool.” While not perfect, this is a great starting point for people who are new to sky replacements. You can do some fine-tuning to get things just to your liking.
Now click and drag in the sky and watch the selection grow until it covers your entire sky.
This selection isn’t going to be perfect, but it’s a good place to start. You can refine things once you create your layer mask. As long as you have most of the sky selected, you’ll be good to go. You can also use the Magic Wand tool to select portions of the sky, and hold [shift] to keep adding new parts to the selection. This works well if you have clouds or other elements besides just the color blue in your sky.
With the sky selected, click the Add Layer Mask button at the bottom of the Layers panel.
The result might surprise you – everything in your picture is now gone except for the sky! (If you still see the original image, remember to click the eye to the left of the Background layer. This will make it invisible, but not remove it from Photoshop.)
Removing everything but the sky is the opposite of what you want to do! The fix for this is simple: invert your layer mask. Select your new layer mask by clicking on the black-and-white thumbnail in the duplicated background layer.
Now invert the mask by pressing Control-I (Command-I on a Mac) or choosing Image -> Adjustments -> Invert from the menus at the top of your screen. Now we’re really making some progress since the sky is gone but the foreground remains intact.
If clouds, birds, or other elements of the original sky are still intact, you can remove them by using the Brush tool on your layer mask. (See Step 3 for details on how to do this.)
Step 2: Insert a better sky
There are a couple of ways to do this next step, and I’m sure you will probably develop your own workflow over time. Since this is just a tutorial to get you started though, it should work for most basic sky replacement.
Choose the File menu and then select Place Embedded. Navigate to the folder on your computer with the image you want and double-click on it. This loads the replacement sky picture into your current Photoshop document. You can then tweak the results to get just the right image you want. The image will load on top of the previous image, and you’ll see it at the top of your Layers panel.
Photoshop layers work like a stack: whatever is on top is, literally, whatever you see on top of your picture. If you want something to appear underneath something else, just click and drag the layers to your liking. In fact, that’s what you have to do with your replacement sky. Click the layer you just inserted and drag it below the duplicated background layer.
Now look at your sky picture! Just like magic, the original sky has gone and the new sky shows up in its place.
Step 3: Clean things up
At this point, there are two common issues that generally need fixing. One is that the foreground has some errors that need correcting, like trees or other objects that are cut off or otherwise not showing up properly. The other is that the replacement sky doesn’t quite fit the empty space.
You can harness the power of Layer Masks to fix the first issue. Tap the Z key to switch to the Zoom tool, and click on your picture a few times to zoom in for a close-up view. Hold the space bar to switch to the Hand tool, and click-and-drag the picture to see the spots that need fixing.
Make sure you select your Layer Mask and tap the B key to switch to the Brush tool. Right-click to adjust the size of your brush and other parameters like hardness and shape.
Now click on the parts of the foreground you want to either remove from the picture or add to the picture. (Press the X key to switch between remove and add mode.) What you’re actually doing is painting white or black on the layer mask: everywhere you paint white is shown, and everywhere you paint black is hidden. You don’t actually see the white or black colors, just the results of painting them onto the image.
If you find that your sky doesn’t quite fill the empty space, you can solve that by just adjusting the size of the sky layer. Click the top layer, the one with the foreground, and adjust the opacity to 30%. That way you can see the background layer, the one with the sky, along with the foreground layer.
The result looks like some kind of weird double-exposure error, but it will look fine once you finish the operation.
Select the layer with the replacement sky and choose Edit -> Free Transform, or press Control-T (Command-T on a Mac). Then use the handles at the corner of the sky layer to enlarge it until it fills the empty space.
After you have resized the sky layer, press the [return] key to lock in the transformation. Then go back to the foreground layer and increase its opacity to 100%. This same process is also a great way to adjust the sky in the background even if there isn’t necessarily anything wrong with it. One example of this is if you want to adjust the sky to emphasize a certain portion where the clouds happen to be more interesting.
Once you get the hang of this process, it’s pretty simple. You can do a lot of custom work simply by editing the layer mask you create in the first step. You can also do this just for fun, like the picture below where I replaced the blue sky behind this building with a giant squirrel. If you have kids, or if you just want to have some fun experimenting on your own, this is a great way to explore some of the capabilities of Photoshop.
Once you try sky replacement using photoshop on your own, I’d love to see some examples of your work. Leave the results in the comments below!