Converting Raw Files in Digital Photography

Many digital cameras can capture images in the camera raw file format, or just raw. This format stores raw picture data from the image sensor without applying any of the usual post-processing that occurs when you shoot using the JPEG format.

Shooting in the raw format offers a number of benefits because you are capturing absolutely all of the data received by your camera's sensor. This makes the raw files superior to any other types of image files. But the downside is that if you want to have images printed at a retail lab or to share them online, you need to process the raw files and then save them in a common image format.

Another downside of raw files is that you can't use them in a word processing, publishing, or presentation program — actually, in any program except photo software that can understand the particular raw language spoken by your camera. (Every manufacturer has its own proprietary raw format, and each new model from that manufacturer produces raw files slightly differently from the previous models.)

You have a couple options for converting raw files:

• Some cameras offer a built-in converter. For example, take a look at the converter available on some Nikon cameras. Although convenient, these tools enable you to control just a few picture attributes. Additionally, there's the issue of having to make judgments about color, exposure, and sharpness on the camera monitor — a small canvas on which to view your work when compared with a computer monitor. Still, having this option is terrific for times when you need to process a raw file on location or when you're in a hurry.

• After downloading the raw files to your computer, you can process them using a photo program that offers a converter. The software provided by your camera manufacturer may provide a raw converter, and many photo-editing programs also offer this tool. The image below offers a look at the raw converter found in Adobe Photoshop, for example. (Pros in the photo industry refer to this tool as ACR, for Adobe Camera Raw.)

How many picture characteristics you can tweak depends on the software, so if you're shopping for a program to handle this task, investigate this feature carefully. Some entry-level programs simply change the file format from raw to a standard format, applying the same picture-characteristic choices that the camera would have used had you taken the photo in the JPEG format originally.

For specifics on selecting conversion settings, you will need to take a look at your camera manual or software manual. You also can find online tutorials for Adobe Camera Raw and other major photo-editing programs that offer raw conversion tools. But here are a few general rules to follow:

• Don’t erase your original raw file. You may someday want to convert the file using different settings, and retaining the raw file means that you always have an original image in pristine condition that you can return to, if necessary.
• The settings you use when making your raw conversion stay with the raw file, sort of like an invisible recipe card. The next time you reopen the file in the converter, you don’t have to go through all the adjustments again; they’re automatically applied as you did them the first time. But because your picture data still is technically “raw,” you can apply a whole new set of adjustments without doing any damage to the picture.
• To retain the highest image quality in the converted file, save it in the TIFF format. Tagged image file format, or TIFF, is a non-destructive format: It preserves as much of the raw file's original image data as possible. That translates to the best image quality, which is why TIFF is the standard format used for professional publishing. Most photo editing, word processing, and publishing programs can work with TIFF files, and most retail labs can print TIFF files as well.

Other nondestructive formats include portable network graphics (PNG) and the Photoshop native format (called PSD, the one created for use in that program). PNG is compatible with many publishing and graphics programs, but few programs other than those from Adobe can work with PSD files. So make your life simple and, unless someone requires you to do otherwise, stick with TIFF.

TIFF does have one downside: Pictures stored in this format are much larger than JPEG files. But that's the price you have to pay if you want to retain your image at its highest quality.

• If you want to use your converted file online, save a copy in the JPEG format. TIFF files don't work online; browsers and email programs can't display them. JPEG, on the other hand, is the universal online photo format and also is fine for taking photos to retail print shops. Just know that unlike TIFF, JPEG is a lossy format. To reduce file sizes, JPEG tosses away some image data as the file is saved. As far as raw conversion goes, the best practice is to save one file in the TIFF format and then save a copy in the JPEG format for online use. (You also may want to reduce the resolution of the JPEG version.)

Before you do any raw conversions — or any photo editing, for that matter — calibrate your monitor. This step ensures that you're seeing an accurate representation of image color, contrast, and brightness.