Fix A Blown-Out Sky In Under 60 Seconds In After Effects
Capturing your foreground under bright conditions can easily blow out the sky in your shot. Learn how to fix the problem with this step-by-step tutorial.
Top image via Shutterstock.
Sky replacement tutorials are a dime a dozen on YouTube, and each educator will often have their own method, using a variety of different effects and techniques. The following method won’t explain how to replace a perfectly captured sky with something a little different. It will, however, show you how to replace a blown-out sky with something more pleasing to the eye.
It’s very easy and very fast. It took me only 54.3 seconds, to be exact, to implement the effect ready for grading and export.
The technique requires a sky that has entirely clipped with no visible blue or clouds. This is usually the result of shooting into the direction of the sun and exposing for the foreground. Of course, this is one shooting practice that you want to avoid. You can correct this by filming with the sun to your back, using a graduated neutral density filter, or using a surplus of lighting to expose for the sky and light the foreground. Alternatively, if you’re unable to film in the opposite direction, you can wait for a later time in the day.
Nonetheless, there may be a reason why these alternative approaches are not possible and you have to shoot facing the sun and work with a blown-out sky. Fear not. Here is how you can fix your footage under sixty seconds.
Before we start, you need a photograph of the sky that is the same size (or larger) than your composition.
Create a New Composition
Import your video file and the sky photo. Bring both files into your timeline, and place the sky beneath the video file.
Luma Key Effect
Add the Luma Key effect to the video file, and change the key type to Key Out Brighter. Then increase the threshold until your image returns with the sky image below now filling the sky in the video file. This is something that will be different with every clip. For my shot, 200 is perfect.
Unfortunately, we are now left with a thin white line around some edges in our image.
Refine Soft Matte
To fix this, add a Refine Soft Matte to the video file. This may be enough for some people. However, in shots like mine that include foliage, you will need to play around with the settings to refine the effect. The settings you will need to adjust depending on your footage are contrast, shift edge, and decontamination amount. If necessary, you can also change the Edge Feather setting on the Luma Key effect in the video file.
Finally, before the video clip is ready for export or grading, adjust the brightness, saturation, or lightness of the sky to match the video file.
This is a great way to quickly replace a blown-out sky, and removing any highlight issues with foliage or small objects that bleed into the blown-out highlights.
- If you have a moving shot, simply track the movement and apply it to the cloud layer.
- If you have sourced your sky image from a stock image website, you may want to add a Gaussian Blur (5-10) to the sky to take the crispness away from the picture.
- When filming, if you know that this shot will ultimately be a “fix it in post” job, make sure you grab a variety of well-exposed sky photographs to use later.
Do you have other tips for correcting a blown-out sky? Share in the comments.