Digital Photo Tips: Determine the Perfect Format for Your Photo Files
By Dave Johnson
MacworldJUN 18, 2006 6:00 pm PDT
The next time you start pining for the good old days of computing, keep this in mind: In 1995 we had to negotiate hundreds of image file formats, and no two imaging programs spoke the same language. These days, with just a handful of common file types for digital photos, we’re living on easy street. Even so, it’s rarely obvious which file format is best for a given image. Here’s a look at the strengths and weaknesses of the three most common digital-photo formats.
Go mainstream with JPEG: This format is the default that digital cameras use to save pictures, and every photo editing or viewing program can read it. Because you’re able to adjust JPEG’s compression level, you can make your files smaller, trading off image quality for portability.
If you’re a casual photographer who shoots, prints, and shares without much serious editing in between, stick with JPEGs. Just be sure to set your camera to capture pictures at the lowest compression, which equates to the highest image quality. You can always reduce the quality later to shrink the file size, but you can’t bring the lost image data back.
TIFF maintains quality: The TIFF image-compression format is revered because it’s lossless–no information is lost during the compression (as opposed to JPEG’s “lossy” compression). TIFF files are larger than comparable JPEGs, but nary a pixel or a shade of lavender is lost when you create, edit, or save a TIFF.
With TIFF, you’ll neither have to deal with the extra baggage that accompanies the RAW format (which we’ll get to in a moment) nor worry about JPEGs throwing away some color information every time you save a photo. For best quality, configure your camera to save shots as TIFF files, and keep saving them that way afterward. Or save pictures on your camera at the best JPEG quality and then, after you edit them on your PC, choose File, Save As and select TIFF. You might lose an almost imperceptible bit of quality with the first JPEG save, but once the file is a TIFF, the quality is locked in.
There is a drawback, however: TIFF files are much larger than JPEGs, and the TIFF format is not as universal as JPEG. You’ll still need to save a copy of the TIFF image as a JPEG if you want to share it via e-mail or to place it on the Web.
Photo fanatics love RAW: To wring every last drop of quality out of your photos, use your camera’s RAW mode (if it has one). RAW is lossless, and it offers more color depth–12 bits of color per pixel, compared with 8 bits per pixel for JPEG and TIFF. This lets you extract more detail from your photos in such editing programs as Adobe Photoshop and Photoshop Elements. Your camera saves RAW files before any white balance, sharpening, or other effects are applied. It’s an unprocessed source file that offers you unlimited creative freedom. Unfortunately, every camera maker has its own flavor of RAW, and sometimes different models from the same camera vendor vary in their handling of RAW. For example, Nikon calls its RAW files ‘NEF’, while Canon uses both ‘CRW’ and ‘CR2’. RAW files also require more work on your part. You’ll have to apply white balance, tweak the colors, and perhaps add sharpening to the image. And since you can’t save your changes to RAW files, you’ll have to keep two copies of your photos–the original RAW version and the edited JPEG or TIFF file. Still, photo fanatics wouldn’t have it any other way.
Try an alternative format: PNG is now the default image-file format for screens captured by Macs, and nearly all browsers can open them. In addition, every photo editing program offers its own proprietary format. Photoshop’s PSD, for instance, is lossless, and it preserves layers, so you can return to an editing project right where you left off. However, such proprietary formats usually can’t be opened outside of the program that created them, so you’ll eventually need to save the files as JPEGs to share them.