Digital Focus: Improve the Background in Your Photos, Part II

If you're frustrated by outdoor photos that consistently feature pale and dreary skies, you're not alone. After all, those photos can be hard to do well. Since the sky is so much brighter than your subject, the camera has to make a choice: If it properly exposes Uncle Ted posing in front of the Pro Rodeo Hall of Fame here in my hometown of Colorado Springs, the sky will no doubt end up looking more anemic than you remember it.

Last week I explained how to take such a photo and improve the color of the sky through a technique called multiplying. This week I wrap up our look at the sky with a more radical approach: outright theft.

Create Your Own Reality

For starters, we're going to need a great photo of the sky. When I see a pretty blue sky, a swirling, cloudy day, a stormy afternoon, or a beautiful sunset, I grab my camera and start shooting. If you fill the frame with nothing but sky, your camera will capture all of the color and intensity that you see through the viewfinder.

Shoot your sky shots with your camera's highest resolution, since you never know what resolution you'll eventually need. You might also want to take some pictures in landscape mode and others in portrait mode so you have a selection of skies for any situation. Store your collection of images in a special folder, and you'll always have options when you want to replace a bland sky.

Excise the Old Sky

First, open your picture in an image editor like Paint Shop Pro. I'm going to use this example.

Just like last week, we'll use the Magic Wand tool to select the sky in the photo. The Magic Wand is a powerful tool for quickly selecting part of a photo because it grabs adjoining pixels that have similar colors. If you want to select someone's red sweater and make it blue, the Magic Wand is an ideal tool, since one click should select the entire sweater.

In my default installation of Paint Shop Pro 7.0, the Magic Wand is the eighth tool down on the vertical tool bar (it resembles a wand with a glowing end). Click the wand to select it, right-click it to bring up the Tools Options dialog box (if it doesn't appear on screen, it's probably nested near the edge of the photo; hover your mouse pointer over it and it will pop open.)

The Tolerance value determines how sensitive the wand is to color changes. If you click on that red sweater with a very low tolerance setting, you'll select only a small part of it because the Magic Wand will ignore nearby pixels unless they are almost exactly the same shade of blue as the pixel you clicked on. If you set the tolerance to a high setting, the Magic Wand will select parts of the sweater that are almost any shade of blue at all. For our purposes, set the tolerance to about 25. If you want each click to capture more of the sky, you can make the tolerance higher.

The Magic Wand's Tool Options dialog box includes an option called Feather. The Feather setting helps smooth the transition across the selected region, and it's a great way to make your stolen sky look more natural. Without feathering your selection, you can end up with a harsh, artificial boundary in your finished picture. Set Feather to one or two pixels.

Finally, we're ready to select the sky. Click the Magic Wand, then move your cursor to the middle of the sky and click again. You should see selection marks appear around a big blotch of sky. Look for parts that aren't selected, hold down the Shift key, and click on them. After a few clicks, you should have the entire sky selected.

Flip Things Around

Now that the old sky is completely selected, I need to tell you that we don't actually want that sky at all. We want to select the rest of the picture, which we'll copy and paste into another image--one that has a better sky. I am using this picture for my better sky.

So why did we select the sky? It's easier to do this because the Magic Wand works so well with the sky's fairly uniform colors. Now that you've got your sky selected, you can use your image editor to "flip" the selected region. In Paint Shop Pro, for instance, choose Selections, Invert. You should see that the foreground is now selected. Copy it into the clipboard by selecting Edit, Copy.

Under a New Sky

Open the photo with the better sky that you want to substitute. Then go back to your original image file and check the resolution. (In Paint Shop Pro, select the image and choose Image, Image Information, then look at the dimensions in pixels.) Now re-size the new sky image to the same pixel size as the old one by choosing Image, Resize and entering the proper number of pixels. If the photos have different aspect ratios, make sure you unselect Maintain Aspect Ratio at the bottom of the dialog box. With a relatively undefined subject, like a skyscape, you can easily get away with changing the aspect ratio without the distortion creating an unnatural appearance. Once you've done that, confirm that the new sky image is selected and choose Edit, Paste as New Layer. Drag the image around as needed until it's positioned properly in the frame, like the one I've made here.

If you like the results, save the composite image to a new file. You're done!