Digital Focus: More Photo Printing Tips

Feature: Picking the Right Print Size

You probably don't want to bring me to the movies; I tend to nitpick. And nothing bugs me more than the way cameras in Hollywood seem to have the magical property of infinite resolution. For example, in a typical spy movie the main character can take a photo--no matter how blurry or how far away--and zoom in on an miniscule detail and create a huge print that's so sharp you could cut a steak with it. Man, that really annoys me.

In real life, factors like resolution, sharpness, and print quality are all inextricably linked. You can't expect to make great 8-by-10-inch prints from a 1-megapixel camera. Don't even bother trying to create poster-size prints unless you start with a multimegapixel image. But there's such a thing as too many pixels. So how much is enough? That's what we'll find out this week.

The Pixel Sweet Spot

Rarely will you know that you want to make an 8 by 10 while you're still framing the shot with your camera. It's only later that you discover you took a great picture and decide to make a print. If you have plenty of pixels, you're in good shape; if you capture the picture at a lower resolution, though, you might be out of luck.

That's why I don't recommend reducing a camera's resolution. For the most part, you should always shoot at your camera's highest pixel resolution.

That said, how many pixels does it take to make a great print? You want to lay down enough pixels to create a sharp, vivid picture. Modern ink jet printers can create excellent results as long as they have about 200 or more pixels per inch to work with. Want to make an 8 by 10? That means your print should be no less than 1600 by 2000 pixels. And since ink jet printers tend to do best with 300 pixels per inch, try to send pictures that measure around 2400 by 3000 pixels.

With that in mind, here's my definitive guide to pixel sizes for printing photos:

Print Size Good Results (200 ppi) Excellent Results (300 ppi)
4 by 6 inches 800 by 1200 pixels (about 1 megapixel) 1200 by 1800 pixels (about 2 megapixels)
5 by 7 inches 1000 by 1400 pixels (about 1.5 megapixels) 1500 by 2100 pixels (about 3 megapixels)
8 by 10 inches 1600 by 2000 pixels (about 3 megapixels) 2400 by 3000 pixels (about 7 megapixels)
11 by 14 inches 2200 by 2800 pixels (about 6 megapixels) 3300 by 4200 pixels (about 14 megapixels)
16 by 20 inches 3200 by 4000 pixels (about 13 megapixels) 4800 by 6000 pixels (about 29 megapixels)

Bigger Isn't Always Better

I know what you're thinking. You're wondering if even more pixels would make for prints that are better yet. After all, why not throw a 1500-by-2100-pixel image at your printer when you're trying to make a 4-by-6 inch print?

You may not like the results: While modern ink jet printers do a very good job of scaling lower resolution images up, they can't scale down very well at all. They get overwhelmed by very high res pictures. Try it yourself: If you send the equivalent of a 400- or 600-pixel-per-inch photo to your printer, you may see weird artifacts and jagged edges. It's best to stay in the 200-to-300-ppi range when printing.

And while we're on the subject, let me reiterate that modern printers can indeed scale a picture quite well. You may hear that you should send pictures to your printer at exactly 200 ppi, 300 ppi, or perhaps an exact multiple of the printer's resolution, like 240 ppi or 1140 ppi. That's all hogwash. For the best results, stick with a print resolution between 200 and 300 ppi. That's all you need to remember. Don't believe me? Try printing a 4 by 6 with 800 by 1200 pixels. Then compare it to a 1000-by-1500-pixel image. If you can see much, if any difference, your eyes are better than mine.

How Big Is the Picture?

So, how large are your image files? There are several ways to find out. First and foremost, check your digital camera's user guide to see the actual pixel sizes for the camera's various resolution modes.

Once the picture files are already on your PC, it's easy to find out. Open a folder with pictures and let the mouse pointer hover over any of the icons that represent a photo. Windows XP should display a tool tip with photo information, including the pixel dimensions. Another option: Right-click on a picture icon and choose Properties from the menu. Then click the Summary tab and click the Advanced button. You'll see a long list of information about the picture, including its pixel dimensions. Or open the file in Jasc's Paint Shop Pro and choose Image, Image Information from the menu.

My favorite method for ensuring a specific print resolution is to use an image editor like Paint Shop Pro to crop a picture to a specific print size.

To try this for yourself, open a picture in Paint Shop Pro and click the Crop tool in the toolbar on the left side of the screen. (It's the third from the top.) In the Tool Options palette at the top of the screen, choose 8 by 10 in from the list of presets, then position and resize the crop frame until you've captured the area you want to print. (If you don't see the Tool Options palette, open it by choosing View, Palettes, Tool Options.) Notice that the print resolution appears in the Tool Options palette; it changes as you make the crop box larger or smaller. Using this method, you can make sure that the print resolution stays high enough to render a high-quality print.

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