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

More image editing tricks. Plus: digital zoom demystified.

Dave Johnson

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!

Dave's Favorites: Humanclock.com

Some Web sites must be experienced firsthand; just reading about them can't convey just how strange, exciting, or trippy they are. That's how I feel about Humanclock.com, a site I recently discovered while surfing the Web in search of photographs of antique clocks. I never found the clocks, but I did uncover a site so unusual that it proves there's no limit to the creativity on the Web.

Here's the idea: Humanclock.com displays the time in an automatically updating Web browser window. The browser updates every minute, showing you a different photo of someone posing with the time.

It's clever and artistic. The Web site's designer hauled a digital camera around his home state of Oregon and took pictures of people posing with numbers taped to a large cardboard sign. The images look like little postcards from familiar places you've never been: shoe stores, public parks, somebody's garage. You can also switch to the real-time "human clock" mode, in which people pose in front of a huge clock face, marking the hours and minutes with their arms.

You can get in the act and submit your own photos to Humanclock.com, or just enjoy the experience. Either way, Humanclock.com is a blast. Check it out.

Q&A: Digital Zoom Demystified

I am trying to photograph scenery and wildlife, but my images are not as clear as I had hoped with my camera's 3.4-megapixel resolution and 6X zoom. Here's the thing: I've found that if I use the highest image size, the detail is quite exquisite as long as I don't use the digital zoom and instead stick just with the optical zoom. Using the digital zoom increases the magnification but it seems to fuzz-up the focus. What do you think?

--Marilyn Lauffer, Denver, Colorado

You hit the nail on the head, Marilyn. An optical zoom uses the camera's optics to magnify the image. You can get very sharp, vibrant images this way, assuming that the camera has a high-quality lens. But a digital zoom cheats: If you turn on the 2X digital zoom, it grabs a block of pixels from the middle of the picture and duplicates them, giving you the impression that the image has been magnified without adding any real information. The result? A blurry picture. My advice is to pretend your camera doesn't even have a digital zoom.

Hot Pic of the Week

Get published, get famous! Each week, we select our favorite reader-submitted photo based on creativity, originality, and technique. Every month, the best of the weekly winners gets a prize valued at between $10 and $100.

A gentle reminder, folks: We disqualify some really wonderful pictures every week because the submissions don't follow the rules. Be sure to include everything we ask for in your e-mail message, including a description of your picture and your complete contact information, or your entry is wasted!

Here's how to enter: Send us your photograph in JPEG format at a resolution no higher than 640 by 480 pixels. Entries at higher resolutions will be immediately disqualified. If necessary, use an image editing program to reduce the file size of your image before e-mailing it to us. Include the title of your photo along with a short description and how you photographed it. Don't forget to send your name, e-mail address, and postal address. Before entering please read the full description of the contest rules and regs.

This Week's Hot Pic: "Stinky Feet," by Vicki Ahlstrom, Margate, New Jersey

Says Vicki's husband, Ulf: "This picture was taken some weeks after the birth of my youngest daughter, Hannah. It's hard to believe that feet can be that small, and yet be so stinky! Vicki took the picture while Hannah and I were sitting on the sofa. We have an HP PhotoSmart 315 digital camera, and we love it!"

We want your feedback! Send your comments, questions, and suggestions about the newsletter itself to comments@bydavejohnson.com. If you have a question that you'd like to see answered in the weekly Q&A, send it to question@bydavejohnson.com.

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