Once you move on from basic photography skills and into more advanced techniques, you’ll find that few things are so useful as sky overlays. No matter what type of photography you enjoy — portraiture, landscapes, architectural photography or any genre — sky overlays will help you to correct those dull, flat skies that so often occur in day-to-day photography. The fact is, you’ll often have very little control over the weather when you decide to take a few photos, and if you are a professional photographer, then you will need to adhere to the appointments that you have set up no matter what the sky looks like.
Fortunately, sky overlays are easy to use, and they are even easier to create. I’ll show you, step by step, how to create your own sky overlays and then use them when needed in your images.
To create a sky overlay, it is as simple as taking a photograph of a beautiful sky. There is no need to search for (and then purchase) stock photos to do this. Simply make a point to take photographs whenever you think the sky looks particularly beautiful. Likely, you’ll want to create several different types of sky photographs — different kinds of clouds, and at different times of day so that you have a collection of overlays to simulate a variety of different weather and lighting conditions.
To take your sky photographs, make sure to just photograph only the sky. Avoid trees, hills and other background objects as this will just create more work for you later on when you need to remove these elements from your images. Additionally, if you exclude background elements from your image, then you will have an easier time creating a balanced exposure. As we all know, it is often difficult to balance an image of the sky that includes a shadowy foreground — often necessitating neutral density filters so that you can manually darken the sky and bring out trees, hills, and other less bright objects.
If you follow this process, making sure to take photographs of the sky whenever it looks particularly interesting to you, then before too long, you’ll have a large collection of photos that you can use as overlays.
To use your sky overlays, start by opening a photo that has a sky you want to replace. Open the sky overlay that you want to use, copy it, and paste into the photo file as a layer. Create a duplicate layer of the original image (the one that needs to have the sky replaced). In Photoshop’s layer panel, the original image should be marked with a small lock symbol. Go ahead and click the small eye symbol by the background layer to hide it, then make sure that you drag each layer so that the duplicate layer is on top of the layer stack, the sky overlay is in the center of the layer stack, and the background layer is on the bottom of the layer stack. When this is finished, click on the duplicate layer to select it so that you can work with it.
In the duplicate layer, use the magic wand tool to select the sky that you want to replace. If the sky has a few clouds, then you’ll need to either adjust the tolerances of the magic wand tool so that it picks up more of the colors in the sky, or failing that, use the lasso or quick select tools to select the sky. Depending, if you need to click more than once to select the entire sky, then you’ll need a tool that allows you to do additive selection either from the tool’s menu or by holding Shift while clicking.
As you select parts of the sky, don’t forget all of the little details — gaps that show between leaves and so forth. Once you have the entire sky selected, then go to the Select Menu and click Inverse to reverse the selection. Now, the foreground elements of your image should be selected, while the sky is not selected.
Making sure that the duplicate layer is still selected in the Layer panel, go to the bottom of the layer panel and click the Layer Mask icon — it should look like a small rectangle with a circle inside. If your layers are in the proper order (duplicate on top, sky overlay in the center, and background or original image on the bottom), then the selected foreground parts will be effectively masked, while the original sky will be replaced with the overlay.
At this point, you may notice that some of the details around the edges of the foreground, where the foreground meets the new sky overlay, aren’t quite right. You can do cleanup with the paint brush tool. Simply select a brush size and fade effect that works well to give the edges between the foreground and overlay a nice blend. Then, make sure that the paint tool’s color is set to either black or white. Black will add to the layer mask, so use it if you need to add more sky to the mask. White removes parts of the mask, so use this color if you have bits of sky where it is not wanted. Make sure to do this work on the duplicate layer, which should have a small layer mask thumbnail next to it in the layer panel.
Once your layer mask is perfected and the sky overlay is blended perfectly to the image, you can move on with other post processing needs, like color correction, or you can export the finished image as a JPEG or other file type for printing or posting online.