Most photographers know that for the maximum in versatility and exposure control, RAW image files are preferable to JPEGs. That said, some photographers like the speed of downloading JPEG files for quick delivery, so for these shooters, we suggest capturing RAW files alongside JPEGs. Still, other photographers insist they ONLY need JPEG files, and while we suggest reevaluating this practice (newspaper photographers being one of the rare exceptions), we recognize that there are times when it can be very helpful to capture JPEG files in camera too. But what JPEG settings should you use? What do those compression and resolution settings mean, exactly? And why do I have compression choices with my RAW files too? Here’s a primer to help you understand image file compression and resolution options.
Raw File Settings
While every camera manufacturer uses its own unique RAW file types (ARW, CRW, NEF), most cameras don’t have a lot of RAW options, although they may include an option for a Large RAW file and a Medium or Small RAW file. These are area resolution settings, and they determine the pixel dimensions of the resulting image file. To take advantage of all the pixels available in a sensor—say, 7952×5304—use the Large RAW image file setting. If your needs are limited to web use or other small file needs, a smaller RAW image file size provides all the benefits of RAW image files without the huge dimensions that may be overkill. That said, if you have the storage capacity and don’t mind big files, it’s probably best to shoot Large RAW files whenever possible in order to maximize printing and imaging options for an image down the road.
The other RAW setting you’ll sometimes see is compression. This is simply a way to minimize file sizes without sacrificing resolution (i.e. pixel dimensions) or the versatility of a RAW image file in general. Turning on RAW compression makes a slight compromise in image quality, but one that’s often very difficult if not impossible to see with the naked eye. I shoot compressed RAW image files for all of my clients and I’ve never seen, nor heard of, any issues. Plus, this takes what would be a 60-plus-megabyte image file and turns it into a much more reasonable sub-40 MB file, without sacrificing any of the control of a RAW file.
Lossless compression, by the way, is the term for a compressed file size that shouldn’t show any visual evidence of having been compressed. Whereas lossy compression, whether in a RAW file, JPEG or any other type of file, will show some visual evidence of having been reduced in size. This is simply because information is thrown out, sacrificed in an effort to reduce the size of the image file. And while true lossless compression is preferred, subtle image quality loss from high-quality lossy compression is likely not visible to the average photographer.
JPEG File Settings
With JPEGs, photographers have a lot more options available in terms of image size and compression.
For image size, these are typically referred to in actual pixel dimensions (i.e. 7952×5304) or as Large, Medium, Small (or L, M, S). A large JPEG will produce a file with physical dimensions that match the largest setting available from a camera’s sensor. To make images that will enlarge for printing as much as possible, it’s good policy to choose the Large file setting. Photographers who are shooting strictly for small print or web use, or those who need to deliver images on a tight deadline or limit the file size of their images, may prefer to shoot Medium JPEGs. Rarely, however, is Small the best choice—simply because a medium-sized JPEG is going to produce such a small file size that storage and transfer won’t be an issue. Only for very limited small web uses that require massive—as in thousands—of files should a photographer consider using the smallest file size setting, and only then after careful consideration. It simply sacrifices too much data to be a good choice in most cases.
Instead, photographers who want to minimize file sizes should consider using a higher resolution setting with compression. In terms of file size, it’s preferable to always use the largest available simply to maximize versatility for a variety of future uses—but medium file sizes will suffice if the specific dimensions of the uses are known, such as a 5×7 print, if those dimensions meet or are exceeded by those produced by the camera’s Medium JPEG setting.
A large image file size can be made smaller with compression. This is usually indicated by terms such as Standard, Fine and Extra Fine. Sometimes, these settings are denoted by icons that represent a smooth curve (extra fine), a slightly stepped curve (Fine) and a stair-stepped angle (Standard). The best JPEG file a camera can produce will be its largest resolution with minimal compression—something along the lines of “Large, Extra Fine.” Once you understand that the pixel dimensions are determined by the size setting (Large, Medium, Small) and the compression is adjusted to Standard, Fine or Extra Fine, you can more easily make deliberate decisions about what settings will work best for your needs. If you’re delivering files quickly but they need to be printed big, try a “Large, Fine” or “Large, Standard” setting. Something that needs to be printed small or used on screen alone can be set to a smaller size with less compression to maximize image quality—along the lines of “Medium, Extra Fine.”
Some cameras, such as the Fujifilm X-Pro2 shown here, offer the option of changing the aspect ratio as well—in this case, from the native 3:2 to 16:9 or 1:1 (square). This is a good way to shrink file sizes simply by throwing out data that’s unwanted based on the intended final crop of the image. The X-Pro2 conveniently shows pixel dimensions, aspect ratio and resulting file size all on a single menu.