How to Use Color Range to Replace the Sky in PhotoShop
This is a PhotoShop CS5.5 Tutorial, but it will work with almost any version of PhotoShop. The key tool used in this tutorial is the “Color Range” tool; however, additional tools and shortcuts will be covered, so you’ll learn several useful tools and techniques. In plain English, we’re going to use “color Range” to select the sky to mask it out and put in a new, much more dramatic sky.
This is the picture I’m going to use for this tutorial (Figure 1). I took it at Key West, Florida on a nice, cloudless day. The view is nice, but isn’t anything unique or drastically memorable.
First, open the photo in Photoshop. Masks don’t work on “background” layers, so the first thing we do is double-click on the layer name “background.” This will open the layer name dialog box (Figure 2). The name will automatically change to “Layer 0” Simply click “OK” and you’re ready to start the tutorial.
Open the photo in Photoshop. Using the standard menu layout, select:
Select -> Color Range (Fig. 3)
You will then get a dialog box showing the selected area/color.
Initially it will be solid black. Use the eyedropper to select a location in the sky. The Color Range should have a fuzziness setting of between 30 and 40. In this example I started at 39 (Fig. 4). You will see the initial part of the sky that was selected by the white at the top of the preview.
On the right of the dialog box are the eyedropper controls (Fig. 5). The eyedropper by itself is the initial selection tool. If you ever want to start over, simply select this tool and click anywhere to get forget your previous selection and start with the newly selected color.
The eyedropper with a + next to it adds additional colors to the selection range. The eyedropper with a - next to it removes the color you select with it from the current selection.
Use the additive eyedropper to select the parts of the sky that were not initially selected. A nice trick I learned to select a range of shades is to select the additive eyedropper, then click and hold while dragging the eyedropper over the various shades you want added. Its faster and easier than trying to individually click and select each shade one at a time.
Now you should have the entire sky selected. The various buildings below should be nicely separated and have a very clean edge in the selection. If you get any similar colors below the horizon, use the subtractive eyedropper to remove those shades. Once you feel you have a good selection, click OK.You will now have the selection marquee showing what is selected (Fig. 6).
With this selected, choose the CHANNELS tab (Fig.7) and click on the NEW ALPHA button to create an alpha channel that you can now edit and clean up to get a perfect selection (red box).
Press "CTRL" and "D" to deselect and see the finished alpha channel (Fig. 8).
Now, with this full sized selection, you'll be able to see the areas you accidentally selected because they were similar to the selected sky. THIS is why you do the alpha. You can now edit the alpha channel to get a very clean and perfect alpha where everything is either pure black or pure white. Simply select the paint brush tool, select pure black and paint in the bottom, being careful to stay away from the border area. Next, change to the pure white and paint in the sky, again staying away from the border area.
Now use the BURN tool, which is selected by clicking and holding on the DODGE tool until the option fly-out panel appears and selecting the pinching hand (fig. 9).Now drag the burn tool over the area of the alpha that has the border between black and white. All the darker grays will begin shifting to black. Now select the "DODGE" tool and do the same on the white part of the border. Once you have the clear edges, you are done creating your mask.
Now you should have a finished alpha, like the one shown to the right (Fig. 10).
To make a selection using this, Press and hold the CTRL key and click on the alpha. You should now get a new marquee around the white parts of your channel. Click on the "Layers" tab to switch back to your original photo. Click the "NEW MASK button at the bottom of the Layers window (Fig. 11) and you will see a mask appear to the right of the photo's icon in the layers window.
The only problem is this mask removes everything EXCEPT the sky. To fix this, we’re going to invert the mask by pressing CTRL and I. Now the sky is masked out, ready for a new one to be inserted(Figure 12).
Next, open a photo of a dramatic, or at least interesting, sky. Here’s the one we’re going to use for this (Fig. 13).
Once it’s open, press CTRL and A to select all of the photo. The selection marquee should be around the entire photo (Fig. 14). Now press CTRL and C to copy the layer.
Across the top of the photo, you should see the tab for the original photo we’ve been working on. Click that tab top return to it. Now press CTRL and V to paste the layer. It’ll be the top layer, so grab the layer thumbnail and drag it below the original “Layer 0” layer. You should now see the original waterfront, with the new sky shining above it (Fig. 15).
With the sky layer still selected, use the MOVE tool to move the sky around until you get a view you like. Press CTRL, SHIFT, and S to open the “Save As” dialog box and name the new PSD. Save the PSD in case you’d like to edit it again in the future.
Finally, save it in the format you want it in, such as Jpeg and you’ve got a great photo to show off! Below is the finished photo, and a close-up of the border area, so you can see how it looks