Looking for an inexpensive way to add interest to a blank wall? Want to show off your digital photos in a way that will really get noticed? The next time you make a print of your favorite photo, don’t settle for a measly 8 by 10 inches. Supersize it. With a little work, you can turn a favorite snapshot into a stunning 16-by-20-inch or larger print—all for less than the cost of a generic print at the poster store.
Know your limits
Your first decision when making a large print is to determine how big you can go before your image loses too much detail. This primarily depends on the number of pixels your camera captures and how closely you pack those pixels together when printing.
Although I usually recommend printing photos at a resolution of 240 pixels per inch (ppi), poster-size prints are typically viewed from farther away. So you can get by with a lower resolution—perhaps even as low as 150 ppi for very large prints. For example, to print a 16-by-20-inch photo at a resolution of 240 ppi (which translates to 3,840 pixels tall by 4,800 pixels wide), you’d need an 18.4-megapixel image. But to print the same image at 180 ppi (or 2,880 pixels by 3,600 pixels), you’d need just 10.3 megapixels. While that’s still high, it’s within the range of what many of the latest consumer cameras are capable of.
But what if you don’t have a 10-megapixel camera? In that case, you’ll need to resize your image, using a process called resampling. When you resample an image to make it bigger, the image editor uses an interpolation algorithm to calculate new pixel data—essentially filling in the blanks around existing pixels so you can reach your intended output size.
Many image editors, including Adobe Photoshop and Photoshop Elements and Apple’s Aperture, will resample images for you. (Unfortunately, you can’t use iPhoto for this type of thing; the program can make photos smaller but not larger. For a workaround to this problem, see “Resample from the Finder.”) Several other programs, such as Alien Skin Software’s
Blow Up ($200) and onOne Software’s
Genuine Fractals ($160), specialize in this type of work. However, unless you enlarge a lot of your photos to billboard-size prints, you probably don’t need to spend the extra money on these programs.
Resampling in Photoshop or Elements
If you use Adobe Photoshop or Photoshop Elements, you can take advantage of the program’s Image Size dialog box to resize and resample your images. To access it in Photoshop, select Image: Image Size. In Elements, select Image: Resize: Image Size.
Test Your Resolution If you can avoid resampling, you should—even if it means printing at a slightly lower resolution. To see just how big you can go without resampling, deselect the Resample Image option and then enter your desired resolution in the Resolution field. Start with 240 ppi. When you enter a resolution, the Document Size pane’s Width and Height measurements will change to reflect the new print size.
If the resulting print size is larger than you need, you’re all set. Simply enter the correct width and height—you’ll end up with a higher resolution than you need, but your image will print fine.
In most cases, though, the resulting print size will be smaller than you want. When this happens, try lowering the resolution—say, to 200 or 180 ppi. If you’re still far from your target print size, you’ll need to resample the picture.
Resample If Necessary While still in the Image Size dialog box, enter a resolution, select the Resample Image option, and then enter the desired output size in the Width or Height field (see “Bigger Is Better”). You’ll notice the image’s pixel dimensions increase as Photoshop calculates new pixels to fill in the missing data. Click on the Resample pull-down menu and select the algorithm you’d like to use. I find that Bicubic Smoother offers the best results for this type of work. When you’re done, click on OK.
Resampling in Aperture
If you’re using Aperture, you’ll set your image size when you export the photo. Unfortunately, you’ll have to calculate the new pixel dimensions yourself—multiply your desired print size (in inches) by your desired resolution.
Be conservative when choosing a resolution. Too much resampling can introduce ugly artifacts into your image. It’s often better to print at 180 ppi than to resample all the way up to 240 ppi.
With a photo selected in Aperture, choose File: Export: Export Version. Choose Edit from the Export Preset pop-up menu. In the Export Presets dialog box, choose Fit Within Pixels from the Size To menu and enter your desired pixel dimensions and resolution. Click on OK, specify where you want the image saved, and then click on the Export Version button.
Printing your photo
You have several options for printing your poster.
Print Shops Your local FedEx Kinko’s can print your image on a large-format ink-jet printer for around $10 per square foot—a 24-by-16-inch image will cost a little over $30. Although you can submit images via the Kinko’s
Web site, I got much better results by visiting a local branch. (Your results will depend on the skills of the employee operating the machine.) You can give Kinko’s the file on a CD or a flash drive. By the way, you don’t have to submit your images at the desired print size, but you’ll have more control over the results if you resize it yourself.
Online Photo Services Many online photo services—such as
Shutterfly —offer poster-size prints, as well as standard sizes. However, after testing several online services, I was most impressed with
Large Format Posters, which specializes in large output. The site provides a wide range of sizes (up to 59 by 100 inches in many cases) and a vast selection of paper types—all at very reasonable rates. It even offers discounts on bulk orders. Its prices are slightly higher than those of some other online photo sites ($29 for a 20-by-30-inch poster), but in my tests, it did a better job. And it’s less expensive than Kinko’s.
Do It Yourself If you plan to make a lot of poster prints and are picky about image quality, you may want to consider purchasing your own large-format printer. Printer prices have dropped considerably over the last few years. For example, you can pick up the HP
DesignJet 130, which produces excellent 24-inch-wide prints, for just $1,300. Printing images yourself is less expensive (once you’ve paid for the printer) and faster, and it gives you much more control over your images’ colors—especially if you take the time to profile your system.
Bigger Is Better: With the Resample Image option turned on in Photoshop’s Image Size dialog box, enter the desired width or height and the desired resolution of your poster image. As you type, the pixel dimensions will change to reflect your image’s new size.
Resample from the Finder
Unlike Aperture, iPhoto can make an image smaller but not bigger. To work around this problem, I’ve created a free program called
To use the Image Resizer program, first drag a copy of the image (or images) you want to resize into a new folder on your desktop (hold down the option key while dragging to create a duplicate of the image, so you don’t accidentally move your original). Then simply drag the duplicate image—or the entire folder—onto the Image Resizer icon.
As with Aperture, you’ll need to calculate the image’s final pixel dimensions yourself. Multiply the desired measurement of the image’s longest side by the desired resolution, and enter this number in the dialog box that appears. (To create a 16-by-20-inch image at 180 ppi, for example, you’d enter
.) Image Resizer will resize the image (or images) and save over the file.
Take Baby Steps If you’ll be enlarging your image significantly—by 150 percent or more—don’t make the whole leap at once. You’ll preserve more detail and get better results by resampling it in 10-percent increments.
Ben Long is the author of Apple Pro Training Series: Aperture 1.5 (Peachpit Press, 2006). ]