Digital Focus: Photo Resizing Tricks

Feature: Resizing Photos in One Dimension

Sometimes you take a picture that almost makes you happy, but it has some problems. That's what happened to me on a recent scuba trip. I managed to salvage one picture in particular with a little clever editing. In the end, what made all the difference was modifying the picture's aspect ratio. In other words, I stretched it.

Stretching photos is usually not something I recommend; but, as you'll see this week, there can be good reasons to give it a try.

If you want to play along at home, save the image file and open it in your favorite image editing program to follow my path from the original, unsatisfying image to the final, stretched version.

Sizing Up the Problems

The picture was taken as a diver swam overhead, passing between my camera and the surface. We were in a cave filled with thousands of fish, and the sunlight created a pretty silhouette of the diver's legs.

Unfortunately, the concept sounds nice--but the actual photo I captured is something of a train wreck. Another diver bumped into me just as I took the picture, and my carefully planned composition was ruined. It's also too dark and the diver's silhouetted fins blend into the shadows.

Crop Out the Distractions

The first thing we can do to resuscitate this picture is to recompose it by cropping. Click the Crop tool (it lives in the third cubby from the top in the toolbar on the left side of the screen), then drag a crop box around the diver that eliminates most of the background and makes that pair of legs the real focal point. You should now have something like this; to apply the crop, double-click anywhere inside the box.

Now that we've eliminated most of the surrounding bits, we need to do something about the contrast. Don't get me wrong; I like the dark silhouette, and I don't want to lose the overall dark tones of the cave. But I want to lighten the picture just enough so that the fins are more clearly defined.

Fix the Lighting

There are a lot of ways to improve the overall lighting and exposure, but I think the Curves tool will suit this image best. Using Curves, we can "remap" the light values at each pixel in the picture. Open the Curves tool by choosing Adjust, Brightness and Contrast, Curves. By default, the curve is a straight line, which indicates that nothing has been changed. If the curve is, well, curved, reset it by clicking the Reset to Defaults button--the curved arrow at the top right of the dialog box.

Now grab the curve and stretch it upwards to increase the brightness. When you like what you see in the preview box, click OK. It's a matter of taste, but I like these values.

Resize in One Dimension

By this point, I was mostly happy with my picture--but it wasn't dramatic enough. I wished I had used a wider lens, or the diver had longer legs. I wanted more diver in my picture!

The solution is easy. Choose Image, Resize. Usually, when you resize a picture, you want both the width and height to change together, or the picture will look like a funhouse mirror. But in this case, let's decouple that relationship.

Remove the check mark from the box marked Lock aspect ratio, then set the dimensions to Percent using the drop-down menu in the Pixel Dimension section of the dialog box and set the height to 100. Set the width to 130 and click OK. You'll get an image that looks something like this, which is a lot closer to what I had in mind when I took the picture.

Dave's Favorites: Budget Image Editing With PhotoFiltre

You don't have to spend $100 on an image editing program to work with your photos.

Everyone knows about the big commercial packages like Adobe Photoshop Elements, Microsoft Digital Image Suite, and Jasc Paint Shop Pro. But there are a number of shareware editors available as well. Many readers swear by IrfanView, for instance, which is free for noncommercial use and available from our Downloads library. Others tell me how much they like a program called PhotoFiltre.

PhotoFiltre is free, yet it's a surprisingly powerful photo editor. (You can make donations to the author via the Web site.) It has all the usual tools, including one-click auto exposure correction, brightness, contrast, and saturation adjustments. You can sharpen and blur, add text, and paint directly on your images.

What I find surprising, though, is how many advanced features the program offers. There's a clone brush, a magic wand for selecting regions of the picture, and even artistic filters that add painterly effects like pastel and watercolor. I really like a filmstrip at the bottom of the screen that you can set to display the contents of a folder, then add pictures from the filmstrip to your workspace just by double-clicking. That makes it easy to work on several pictures at once.

What doesn't PhotoFiltre offer? For starters, it lacks the kind of smart, uncluttered interface you'll find in a commercial editor. The program feels a bit crowded and complex, as if the designer felt the urge to put every single menu item in button form somewhere on the screen. It also lacks an "edge tracking" selection tool and support for layers, and that limits your ability to make sophisticated changes to your picture.

Despite the program's weaknesses, it's definitely worth a try--especially if you haven't invested in one of the top commercial photo editors.

Q&A: What Are Effective Megapixels?

I am interested in getting an 8-megapixel camera. Some of the technical descriptions of the cameras I am considering say they are "8 effective megapixels." What are "effective megapixels?" Does that mean the camera actually has a 6 or 7 megapixel CCD and uses firmware to enhance the image up to 8 megapixels?

--Carl Mahan, Georgetown, Kentucky

Think of effective megapixel as an honest appraisal of the camera's resolution after the useless pixels on the image sensor are discounted. Here's the deal: A camera's CCD may have 8.5 million pixels on it, but some of them are on the edges and don't contribute to the picture. So the camera might be advertised as "8.5 megapixel, 8 effective megapixel." The second number is the one you care about.

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 $15 and $50.

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 regulations.

This Week's Hot Pic: "Spokes," by Tracy Brown, Ashaway, Rhode Island

About this week's winning photo, Tracy says: "I took this shot of a hub of a mountain bike wheel while getting the bike ready for spring. I liked the geometry of the spokes as they radiate out to the rim and felt it was an ideal candidate for black-and-white treatment."

I want your feedback! Send your comments, questions, and suggestions about Digital Focus 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. And be sure to sign up to have the Digital Focus Newsletter e-mailed to you each week.
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