Photography in the digital age
Part I: The three most important words in digital photography: Resolution, Resolution, Resolution
by Gary Clites
Originally published in the Dow Jones Newspaper Fund's Adviser Update, Spring 2003
Digital photography has revolutionized the world of journalism both in the professional world and for the student publications we produce. Dealing with this new technology has, however, introduced issues into newspaper, yearbook and magazine production most of us were never really trained to handle. How you deal with digital photos, however, can directly affect the quality of your publication as well as your computers and other technology.
Following is the first in a series of articles designed to address some of the key issues in using digital photography in scholastic communications.
Digital versus film: What’s the real difference?
When it comes to the artistic and journalistic elements of photography, not a lot. A good photo is still a good photo. Have you noticed, however, that since the advent of electronic photography, the quality of shots in some student publications have improved markedly, while those in some others have declined?
Whether you shoot a picture with a digital camera or scan a developed print or slide into the computer using a scanner, at the point when you download that photo to a computer, the shot ceases being a normal photo and is transformed into a digital computer file. The first step in creating successful shots for publication in the 21st Century is to begin thinking of your photos not just as art, but as small digital files. It is how you handle photos as a computer file that can make digital photography a benefit or a drag on your publication.
DPI, LPI, SPI and Pixels
Resolution is a description of the output quality of an image. Unfortunately, the digital photo and printing industries use several competing terms for resolution and that has created tremendous confusion. Dots Per Inch (DPI) is a printing term and refers to the number of dots of image that can actually be printed on a page; Pixels Per Inch (PPI) is a computer terms indicating the number of elements of screen image that can be delivered to the computer; Samples Per Inch (SPI) is only used for scanners and indicates the amount of photo elements a scanner can collect; and Lines Per Inch (LPI) is a printer’s term indicating the amount of resolution available for creation of a halftone image in a finished publication.
Confused yet? You will be when I add the fact that digital camera and scanner manufacturers ignore all of this and sell their wares according to the maximum number of pixels possible in the largest photo they can manage. In other words, a camera advertised as offering a 3-megapixel image does not shoot at 3-million PPI. Rather, if the largest photo it can shoot is an 8-by-10 (and some cameras shoot much larger photos), it can gather up to 3-million pixels for that photo.
How much resolution do I need?
That is one of the key questions in dealing with photos for publication. When discussing publications, most printers prefer to deal in Dots Per Inch rather than the other terms above. What DPI do you need to work in? I can’t tell you, but your printer can. The first step any advisor should take with regard to dealing with photo files is to call their printer and ask what is the highest output resolution at which they can print photos. For most newspaper printers, that will fall somewhere between 150 and 300 DPI.
Won’t it help if I save my files in a much higher resolution? Not a bit. If your printer’s highest printing output is 150 DPI, you will never be able to improve upon that resolution in your photos. And even with today’s massive computer hard drives, the thousands of photos publications take can eat up computer space quickly. Most of us don’t need to save or deal with our photos in nearly as high a resolution as we currently do. It makes sense, then, to find out your printer’s maximum output resolution and to adjust computer files to that DPI or to one just a bit higher as soon as you download them to the computer.
At what resolution should I shoot photos?
The number of pixels you shoot in and the number of DPI files end up set for are not the same. A pixel and a dot are not exactly equivalent, though they are close. It is a good idea, therefore, to initially shoot photos at a higher resolution. It is not, however, necessary to shoot at 3-megapixels if you plan to end up at 300 DPI or less. Therefore, if you have a high resolution camera, feel free to set it to a medium resolution setting (since all cameras are different, it is impossible to tell you exactly where). Test a few shots. As long as they end up in the camera with at least the DPI you need in the size photo you deal with, they’ll do fine. Better, when buying cameras purely for publication use, feel free to buy mid-level cameras with a maximum output of 2-megapixels, say, and save yourself several hundred dollars per unit.
How do I adjust the resolution of my photos?
Scanning programs differ radically, but most allow you to set a target output resolution as you scan. Look in the scanning control window for such an option. Failing that, look inside the program’s preferences file and set the scanner for the DPI your printer has indicated. If that won’t work, scan materials, then adjust their resolution using PhotoShop as described below.
For shots from a digital camera, it is best to download them to the computer, then set the output resolution using the photo manipulation program you use already. For most of us, that is Adobe PhotoShop. In PhotoShop, open the photo. Under “Image” in the pull-down menu, open the “Image Size” control panel. Change the size of the photo to nearly the size you’ll actually use (maybe a hair larger). That’s crucial, since using the right resolution at the wrong size can cause tremendous problems. Finally, set the resolution you need (use “pixels-per-inch”). Now you have a file in the correct resolution. Other programs should work similarly.
Resolution is only one issue in creating good digital pictures, but when it comes to preparing photos for publication, it is the most crucial. Look in this space in the future for more tips on making those digital photos work for your publication.
© Gary Clites, 2003