Replacing a Sky with Photoshop

Sometimes it’s necessary to replace elements in a photograph. Sometimes it’s just fun! Whether for fun or necessity, here’s a fairly easy way to go about replacing a piece of a photo, in this case, the sky. I took the example photo on a typical Texas summer day when there wasn’t a cloud in the sky and I’d like to liven the sky up, just a bit.

Begin by duplicating your main layer (Ctrl + J on PC; Cmd + J on Mac). This layer will become your mask layer. The next thing you’ll want to do is to actually create that mask, masking out the area you want to replace. Like everything in photo editing programs, Photoshop in particular, there are multiple ways to do this. I won’t go into masking or the various ways to make a mask in this article, but I find Calculations (Image > Calculations) to be the most effective, for me, most of the time.

Calculations put your mask on an Alpha Channel, which, to simplify things, is a channel, separate from the regular color channel s (in this case Red, Green and Blue, or RGB), which allows you to load and save selections. You can also make a mask using the color channels themselves – no matter how you do it, once you have the area you want to replace masked out; you’ll need to add the mask to your image. When working with Calculations or using Channels to create your mask, you can simply select the Load Channel as a Selection button:

You can also add the mask to the layer with the good old Add Layer Mask option!

Hold down the Alt (Opt on Mac) key and select, via left mouse click, the mask itself. This will bring up the mask itself as your image.

Go to Filter > Blur > Gaussian Blur and blur the filter, slightly. You want to blend the edges between black & white slightly, here, not obliterate them entirely.

No matter the method, once you have your mask added to your mask layer, you’re ready to add in your new element, here, a new cloudy sky. If you do a lot of retouching or restoration work, it’s a good idea, essential, in fact, to build up a library of images that you can use as replacements. It’s never, ever okay to just go and take someone else’s image from the Internet. It doesn’t matter if you’re going to blow it up so big, or small, invert it, flip it, whatever, that you think it’ll never be recognized. It’s stealing. Build your own image library through your own photography, purchased and public domain images. A great source, of course, are the images provided by Wetzel & Company, Inc.

Select (Alt or Opt +A) and copy (Alt or Opt +C) your replacement image. Now move to the main image and select the mask (mouse click over mask while holding down Ctrl on the keyboard if on PC; Cmd on a Mac). Make sure the area you’re going to insert the image into is selected. You may need to invert the selection (Ctrl or Cmd + I). Go to Edit > Paste Special > Paste Into.

The replacement image you previously selected, in this instance the sky, will appear in the selected area of your main image – which will hopefully be in the sky! If not, just go back a step and invert the selection (again, Ctrl or Cmd +I) and repeat the Paste Into step. Now Transform the replacement image (Ctrl or Cmd + T) and adjust the image to fit the area.