A RAW file is what the name suggests: raw, unprocessed data. It contains the image data exactly as captured on your camera sensor. Any white balance, Picture Style or other settings that you might have applied are only appended to the image file. This means they can be changed later using RAW processing software such as Canon's Digital Photo Professional (DPP) or Adobe® Photoshop® (with up-to-date Adobe Camera Raw plug-in), among others.
A RAW file is often referred to as "digital negative" because the data can be processed and printed in different ways to produce different results, just like the negative from a film camera. Also like a film negative, the RAW file never changes. When you open a RAW file in a software application, process and edit it and then save it, this creates a new file on your computer (usually your choice of a JPEG or TIFF). The original RAW file is unchanged, and can be opened again at any time and worked on to produce a completely different result.
The letters RAW do not stand for anything – it's just a convention that RAW is usually written in capital letters – and the names of RAW files from Canon cameras do not end in .RAW. Instead, until the DIGIC 8 processor was introduced with the EOS M50, Canon cameras saved RAW files in the .CR2 format. Some cameras also offered the option of smaller, lower-resolution "medium" (M-RAW) and "small" (S-RAW) files. These two types of files have most of the advantages of a RAW file but because they are lower resolution they take up less storage space.
The DIGIC 8 processor enabled a .CR3 file format, with a C-RAW option that captures the same resolution but produces 35–55% smaller files, saving storage space on your memory card. (To do this, however, C-RAW uses lossy compression – that is, it discards some image information. More about this shortly.)
The RAW files from different camera models are not exactly the same, even if they are the same file format (CR2 or CR3). For this reason, RAW processing software such as DPP is regularly updated to support new camera models, so if you have a new camera, do check for updates to DPP and download the latest version.
A number of EOS cameras give you the option of processing RAW images in-camera, which is great if you want JPEGs to share and prefer to customise settings such as white balance, brightness and noise reduction yourself rather than just using your camera's built-in JPEG settings. Processing RAW files on your computer instead of in-camera, though, gives you the advantages of a larger screen and greater processing power.
Advantages of RAW