The Raw Truth About JPEG: Choosing an Image Format
Debate continues among photographers about the pros and cons of shooting JPEG versus Raw images. Opinions vary depending on who you ask. This can be particularly confusing for new photographers trying to nail down an efficient workflow. The bottom line is that the file format you choose to capture your photographs with will have a significant impact on your workflow. Let’s take a few minutes to examine both formats!
Joint Photographic Expert Group (JPEG)
The original JPEG file format was created in 1992 (approved by the ISO setting body in 1994) and is supported by virtually all image editing software and operating systems currently on the market today. This makes it incredibly convenient to use for consumers and professional photographers alike. A big advantage of shooting JPEG is that your camera applies all of the necessary processing adjustments prior to being saved. Processing adjustments vary from camera-to-camera and manufacturer-to-manufacturer; however the most common enhancements include increasing saturation, bumping up the contrast and sharpening the image. Consider how this can significantly speed up a professional photographer’s workflow; especially if he or she is shooting thousands of images each week!
This advantage can also be a distinct disadvantage. If your exposures are not spot-on, there is very little flex to be had if you decide you want to make processing adjustments later on. JPEG images are compressed to 8-bits per channel before even being written to the memory card. The amount of compression depends on several factors; however your camera essentially throws away approximately 1/3 of the file information before writing it to the memory card. This lossy compression reduces the overall file size, but it comes with a huge cost. An 8-bit JPEG has a mere 256 exposure values (0-255). In contrast, a Raw image can contain up to 32, 768 different shades between pure black and white. To make matters worse, JPEG files are recompressed each time they are saved. In the example below, I took a high-resolution image and saved it as a JPEG using Photoshop. Take a look at the sharp edge detail around the buildings and the smooth gradient in the sky.
I resaved the image separately 10, 20, 30, 40 and 50 times using the highest setting available in Photoshop (12). As you can see, artifacts in the image start to become obvious even after the image has only been resaved 10 times. The photograph has been virtually destroyed after saving it just 20 times. Admittedly, resaving an image like this is extreme, but think about it for a moment; how many times have you opened a JPEG image, made a quick change and then resaved it? This can create an archival problem for photographers interested in maintaining the quality of their work during the editing process. JPEG shooters should always make working copies of their files and preserve the originals.
The Raw Deal
Raw images on the other hand contain all of the original file data (with a few exceptions). The camera simply writes the data straight to the memory card without applying compression or processing adjustments. Changes to a Raw image are typically written to a sidecar file. Depending on your point of view, this might be considered a good or bad thing. A typical Raw image usually looks dull and lacks the “pop” that most photographers look for. I know several serious photographers who have been put off by this and opt to shoot JPEGs instead. Think of Raw image files as you would traditional film negatives. All of the data your camera’s image sensor captured are present; it just needs to be processed. Photographers shooting in Raw format have to apply standard processing adjustments to their images before they can be presented. Typical workflow adjustments include exposure and lighting tweaks, bumping up the saturation, increasing contrast and sharpening.
A downside to shooting Raw images is that there is no set standard for what a Raw file should look like. Every camera manufacturer has its own proprietary Raw file format and software to open it. It is not uncommon for a camera manufacturer to have different versions of a Raw image file for the same camera model! Companies that produce image editing software have to work double time to keep up with new file formats that hit the market each year. This could potentially be a serious problem for photographers who need to share their Raw files with colleagues or are concerned about the long-term storage of their work. Photographers interested in archiving their images want to be assured that they can open and re-edit their work years down the line.
Are You Confused Yet?
Are you even more confused about which file format to use? Putting all the technical aspects of both file formats aside, this issue really boils down to speed versus control. Shooting JPEG images offers a slightly faster workflow while shooting in Raw format offers more control.
When Adobe released Lightroom, the benefits of shooting straight in-camera JPEGs (primarily for speed and convenience) were greatly diminished. Lightroom has made it possible to quickly process large numbers of images and save copies as JPEGs. With very few exceptions, I have chosen to capture nearly all of my photographs in Raw format because of the control it offers. Shooting Raw makes it a cinch to adjust the color temperature, exposure (up to several stops in either direction), brightness, contrast and saturation of my shots in Adobe Camera Raw (ACR) or Lightroom. All digital image files start out as Raw data files before the camera converts them to JPEGs using in-camera preset processing and conversion formulas. The way I see it, shooting straight JPEG images offers speed over control while shooting Raw images offers control over speed. Which do you prefer?
I am fairly methodical about properly setting the color temperature and exposure while I am shooting; however mistakes happen. It is not uncommon to have to make basic adjustments to an otherwise wonderful series of images. I run into this challenge when I photograph portraits against a setting sun for example. Dusk and dawn lighting changes so quickly and is so dynamic that it is easy to slightly underexpose or overexpose a string of shots. Since 12-bit or 14-bit Raw images are lossless and contain all the information available in the original data file, you have a great deal more latitude than with compressed 8-bit JPEGs.
Just to experiment, take an underexposed JPEG image and try to increase the exposure by couple of stops. While you are at it, crank on the fill lighting and brightness sliders to even things out. You usually wind up with a mushy mess. Try the same thing with a Raw image and you can typically recover the lost exposure without damaging the image.
If you need make a large number of JPEGs available to a client, you can quickly convert the original Raw files using Lightroom’s Export tool. Each photographer must decide which image format works best for them based on what they are photographing. There are still several good reasons to shoot straight JPEG images; however I highly recommend shooting in Raw format if you want total control over how your images are processed.
Digital Negative Format (DNG)
I mentioned that one of the downsides to shooting in Raw format is that it is proprietary. If your camera manufacturer goes out of business or simply decides to stop supporting a particular Raw file format; you will may have difficulty finding software that supports it in the future. There is also the issue of sharing Raw files with others who may not have the appropriate viewer to open the images. This is where a fairly new Digital Negative format comes to the rescue!
The Digital Negative (DNG) format was created by Adobe as a way to bring the hundreds of Raw file formats under one umbrella. A Digital Negative is simply a non-destructive, uncompressed wrapper. Digital Negatives are convenient to share with others because the format has been made publicly available and is considered an open standard. Unlike Raw files that are manufacturer specific, DNGs do not require side car files to keep track of changes and should be around (and supported) for a long time. Converting your Raw images to DNGs allows you to easily share your work with other photographers and clients, since they will not need proprietary software to open them, and insures that you will be able to read your files (without manufacturer specific software) for years to come.
Fortunately, Lightroom provides a way to automatically convert your Raw images into Digital Negatives seamlessly while they are being imported into your Lightroom library for the first time. Adobe also offers a free Digital Negative Converter for photographers who do not have Adobe Camera Raw (ACR) or Lightroom. JPEG shooters may also benefit from converting their images to Digital Negatives. You can’t recover the data lost to compression or extend the dynamic range of an 8-bit JPEG image by converting to DNG; however it might be a smart way to archive your files. Only time will tell if this ends up being a good option for JPEG shooters. Head over to Adobe’s website and read the white paper for manufacturers for more details on the DNG format. DPBestFlow.org also provides an excellent, comprehensive overview of the DNG file format.
Assess – Decide – Shoot
Every photographer has to assess their own workflow and decide what image format that works best for them based on the type of work they do. Fortunately most of today’s DSLR cameras allow you to easily switch between image formats and even shoot Raw + JPEG if the situation dictates it. Having a good understanding of each file type is the first step toward developing an efficient workflow that will stand the test of time.
About the Author
Steve Paxton lives with his wife and two children in the Seattle area. Steve has been a photographer for nearly 20 years. His experience ranges from wedding and portrait work to landscape photography.
Steve owns and manages the F/Stop Spot; a website dedicated to supporting photographers of all skill levels. You can find more of Steve’s work at Paxton Prints and Paxton Portraits.