The short answer
A RAW file is not really an image in the sense a JPG is. It's a pile of measurements: the essentially unprocessed readings from every individual photosite on your camera's sensor, saved before the camera decides what the picture should look like. A JPEG arrives already white-balanced, colour-graded, sharpened and compressed. A RAW file hands those decisions back to you — or to your editing software — later, on a bigger screen. Think of it as a digital negative rather than a finished print.
That single idea explains almost everything else: why RAW files are big, why they seem to be "flat" and low-contrast when you first open one, and why every camera brand stores them in a different, proprietary container.
What's actually inside a RAW file
Strip away the marketing and a RAW file holds a handful of distinct kinds of data:
- Un-demosaiced sensor data. Most sensors are covered by a colour filter array (a Bayer pattern) where each photosite records only red, green or blue. The RAW stores this mosaic untouched; the camera's processor, or your RAW converter, later interpolates the missing colours to build a full-colour image.
- Higher bit depth. Typical cameras capture 12 or 14 bits per channel — 4,096 or 16,384 brightness levels. A JPEG is 8 bits, or 256 levels. Those extra levels are where highlight recovery and shadow lifting come from.
- Unbaked white balance. The camera records the colour of the light as metadata rather than burning it into the pixels, so a RAW file can be re-white-balanced to tungsten, daylight or shade with no quality loss. Do the same repeatedly to a JPEG and you start compounding errors.
- Metadata, not pixels. Lens correction profiles, ISO, shutter speed, the camera's own picture-style preview, and often a full-size embedded JPEG thumbnail — that thumbnail is why your camera and some file browsers can show a RAW preview at all.
- Optional lossless compression. Formats like Canon's CR3, Nikon's NEF and Adobe DNG use lossless or near-lossless compression, so a 14-bit file doesn't balloon to a full uncompressed size.
Why every camera brand has its own RAW format
There is no single RAW standard. Each manufacturer defines its own container, and the extension tells you which decoder you need:
- .CR2 — Canon, used from 2004 until about 2018.
- .CR3 — Canon's newer format (2018 onward), based on the ISO Base Media File Format and often smaller than CR2.
- .NEF — Nikon Electronic Format.
- .ARW — Sony Alpha RAW.
- .RAF — Fujifilm, unusual because it stores the data in a rotated layout matched to the X-Trans sensor.
- .ORF — Olympus and OM System.
- .RW2 — Panasonic Lumix.
- .DNG — Adobe's open Digital Negative, also used by Leica, Ricoh, Pentax and Apple ProRAW.
- .PEF / .X3F — Pentax and Sigma respectively.
The practical consequence: a RAW file is only as portable as the software that understands its brand. That's exactly why DNG exists — as a vendor-neutral destination to convert to — and why converting RAW to a universal format is often the simplest fix when you just need the photo to open somewhere.
RAW vs the JPEG your camera also saves
Many cameras can write RAW and JPEG at the same time, which is genuinely useful: the RAW is your archive, and the JPEG is the instant share. The trade-offs are worth knowing before you switch to RAW-only.
- File size. A 24 MP RAW is typically 20–35 MB; the matching JPEG is roughly 6–12 MB. On a long trip that difference decides how many memory cards you carry.
- Editing headroom. Recovering a blown sky or lifting a dark interior is easy from RAW and often impossible from JPEG, where clipped highlights are simply gone.
- Speed. JPEGs are ready instantly; RAW needs a conversion step before it can be shared, printed or uploaded.
- Compatibility. JPEG opens everywhere on earth. RAW needs a decoder, which is why blank thumbnails and "unsupported format" errors are so common.
When RAW is the wrong choice
RAW is a workflow, not a virtue. It's overkill when you're shooting hundreds of snapshots at a birthday party, when you need to hand photos over on the spot, or when storage is tight. Photojournalists on deadline, real-estate agents delivering images same-day, and anyone shooting to post straight to social media often do better with straight JPEG. RAW earns its keep when the light is difficult, the exposure is uncertain, or you plan to grade the image carefully afterwards.
Four myths about RAW files
- "RAW is always sharper." Sharpness comes from the lens, the focus and the shutter speed, not the file format. RAW preserves more detail to work with, but a soft frame stays soft.
- "A RAW file already looks like the scene." Unprocessed, a RAW often looks flat and slightly dull. The punchy version your camera showed you was the JPEG preview, with picture style applied.
- "You can fix any mistake in RAW." Expect roughly one to two stops of recovery at each end. Blow the exposure by five stops and the highlights are gone, exactly as in a JPEG.
- "RAW is only for professionals." Anyone who occasionally misses an exposure can benefit. The real costs are disk space and one extra conversion step, nothing more.
How to open a RAW file when you don't have editing software
You don't need a subscription. The converter at the top of this page decodes RAW in your browser using WebAssembly, renders it with a sensible baseline and exports a JPG — useful when a client sends you a CR3, or a friend hands you an NEF, and you just need to see and share the photo. For a daily editing workflow, dedicated RAW developers such as Adobe Camera Raw, Capture One, DxO PhotoLab or the free Darktable and RawTherapee give you far more control. But for "open it and get a JPG", a browser tool is the least friction.
If you want the detail on how the two formats compare for editing, read RAW vs JPEG. If your files are already in a specific brand's format, the CR2, NEF and ARW converters each handle one type.