What is… a Raw File? [Video]

Shooting Raw can transform your photography. Matt explains what you need to know



Every current DSLR and Compact System Camera, and also many compacts, give you the opportunity to store the images you capture in either Raw or JPEG format.

JPEG is the default option and the one you’re probably already used to, giving you images you can publish online or print straight away.

Raw files are a little different in that the camera has done part of the work but you need to essentially finish off the processing yourself. It’s similar to a negative from a roll of film in that bones of the image are there but you still have control over exactly how you create the image from it.

Clearly this involves more work and effort so why would you want to do this? In short, it gives you a lot more control over the finished result. Instead of deciding things like colour, white balance, noise reduction and sharpening at the time of capture, you can tweak these with greater control on a computer later on.

Raw files contain more data than JPEGs and they are designed to be malleable. Raw images are generally stored in a 12 or 14bit format, compared to the 8bits that’s standard for JPEGs. This means there is more scope for greater colour information in Raw files.

Like JPEGs, Raw files are typically compressed in camera, although the process is different for the two. JPEGs are usually compressed by a system known as lossy compression, which means some information is discarded and guessed using the value of neighbouring pixels. With Raw files, you may have the option of saving images with the higher quality lossless compression system, which means information within the file is reorganized for greater efficiency without image details actually being lost. This creates higher-quality images but at the expense of file size.

With Raw files you can typically regain details from highlights, brighten shadows and make colour corrections, viewing the results in real time and adjusting other processing options as you do this to make sure the image stays fine.

Not only that but because any edits you make to a Raw file area saved alongside the file rather than as part of it, you can revisit a Raw file as many times as you like and not worry about the original file losing its quality. If you were to make the same edits to a JPEG as you would to a Raw file, you’ll soon find they wouldn’t hold up as well.

The exact level of control you have over your Raw file all depends on the software you use to process it. You can use an industry-standard program such as Adobe Photoshop or Lightroom, the software that comes with your camera or something else, but all should offer some form of control over exposure, white balance, noise reduction and sharpening.

Some programs will even automaticity know the characteristics of the lens you used to capture your image and can correct aberrations such as vignetting, distortion and chromatic aberration.

You don’t even need to use a computer to process these as many of today’s cameras offer Raw processing as standard. You typically won’t have the same level of control as you would on a computer, but it’s useful if you want to quickly process and save a number of different versions of the same image as JPEGs.

Once you’re done with editing, you can also save your Raw files as lossless TIFF files for excellent quality or as JPEGs when size and compatibility with different display devices is a priority. You should also hang on to your Raw files, though, as you may want to process them again in future using a different program.

It’s worth bearing in mind that you don’t always need to shoot Raw images as many camera’s today are more than capable of processing JPEG files well. The safest option is to shoot Raw and JPEG images at the same time so that you can use the JPEG file if you’re happy with it and process the Raw file if you’re not.


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