File formats explained
There are number of different file formats in use in photography, particularly when you move on to the editing phase. There is no ‘best’ file format exactly because it depends on the context and the particular stage in your shooting and editing workflow. So let’s take a look at these different file formats in detail.
JPEG: the universal constant
Every camera, smartphone and action camera can shoot JPEG files. They can be shared with anyone, viewed on any device and are compatible with any photo-edting tool. If you want to share a photo with other people or the world at large, share a JPEG.
But the JPEG format has technical limitations. It uses a ‘lossy’ compression system which will bring a visible deterioration in image quality if you repeatedly edit and resave the same file. No-one is likely to do that because you would always return to the original to re-edit it, not keep editing a copy of a copy of a copy etc. Still, this generational quality loss could be a thing.
JPEG is also an 8-bit file format. This means its capacity for recording highly nuanced shades and colors is limited. Unedited JPEGs straight from the camera will look fine because they have been created from a much larger range of tones and colors captured by the camera sensor, but if you then start to apply heavy image manipulation techniques you can soon start to see banding or posterisation in areas of the image that should show smooth tonal progressions.
Basically, a JPEG photo is a cut-down version of the full range of tones and colors captured by the camera, reduced to a file that can display on any device and is small enough to email, post online or on social media channels.
JPEGs can also be perfectly good enough to print, even at large sizes, because that depends more on the resolution of the camera – the JPEG format itself is not a limitation. So even if you shoot RAW files with your camera (see the next section), the JPEG format can still be the best format for sharing your finished, edited, perfected images.
HEIC/HEIF: an emerging standard
This is like a modern alternative to the JPEG format. The files are smaller, the compression is less destructive. You’ll find it on iPhones and some newer cameras. And it’s not all about efficiency either. These files can be 8-bit, like JPEGs, but they also support 10-bit color, so there is potential here for highly compressed image files which are also able to survive heavy editing better than JPEGs.
Having said that, this format is a long way from universal acceptance, and the 10-bit editing potential has yet to be explored in any depth. It’s certainly an interesting format for the future, but at the moment it’s not close to toppling the JPEG format as the default image file format.
RAW files: the expert’s choice
With the exception of inexpensive point and shoot cameras, most cameras – DSLRs and mirrorless cameras, certainly – will let you shoot both JPEGs and RAW files. Many photographers shoot both at the same time – JPEGs for quick sharing, RAW files for editing and enhancing.
RAW files are basically the image as captured by the sensor itself with no further processing. With JPEGs, the camera does the processing internally based on your camera settings; with RAW files you need to do the processing yourself later using RAW processing software like Lightroom, Adobe Camera Raw, Capture One or others on your computer.
RAW files contain a wider range of tones than JPEGs, allowing for a certain amount of shadow and highlight recovery with difficult or high contrast scenes, and the full color range captured by the sensor, so that you can choose the white balance setting later, regardless of how it was set on the camera.
RAW files are also captured at a greater bit-depth, typically 14-bit, sometimes 12-bit and occasionally 16-bit, depending on the camera. This makes them much more resilient when editing, so that you no longer have to worry about strong adjustments or manipulation.
Annoyingly, each camera maker produces its own RAW ‘format’. Nikon uses. the .NEF format, Sony uses .ARW, Canon uses .CR3 and so on. Worse, each camera introduces its own variant of these formats which are themselves unique. So that while RAW processing software can open and edit all these different file formats, whenever a new camera comes out the publishers have to issue an update to add support for that camera, which may not happen straight away.
In any event, for serious photographers the RAW format is the most popular choice. RAW files are larger than JPEGs, but not excessively so, so they don’t really bring any particular storage headaches.
Adobe DNG format: useful but not universal
Adobe’s DNG (Digital NeGative) format was originally seen as a ‘universal’ RAW file format that could replace the multiple camera-specific RAW formats on the market. But while some camera makers have adopted the DNG format for use in their cameras, notably Pentax and Leica, most stick to their own proprietary RAW formats.
Adobe Lightroom does offer the opportunity to convert RAW files into the DNG format when you import them into your Lightroom catalog, but there seems little point given that Lightroom supports all the existing camera RAW formats natively anyway.
The DNG format has taken on another role in image editing, specifically the ‘Linear DNG’ variant. This is a part-processed RAW file which has the advantage of allowing partial processing for denoising, for example, but otherwise retaining all the advantages and flexibility of regular RAW files.
DxO has made great use of the Linear DNG format in its PureRAW 6 software, which denoises RAW files and applies bespoke lens currections for the ultimate in RAW quality.
Adobe DNG files are about the same size as regular RAW files, but Linear DNG files are typically 2-4 times larger because the RAW data has been ‘demosaiced’ into full color RGB data for each pixel. DxO has, however, introduced a ‘high fidelity’ compressed DNG format which produces files no larger than the original RAW files and often a lot smaller.
TIFF files: big, but a long-standing favourite for high-quaity editing
The TIFF format, like the JPEG format, can be viewed directly without the need for processing, or an embedded preview (which RAW files have). They offer the potential for higher quality than JPEG files, but only at the cost of much larger file sizes.
One reason for the extra quality potential is that TIFF files use ‘lossless’ compression or no compression at all. You don’t get the same kind of generational loss with re-editing TIFF files that you do with JPEGs, though it’s still best to return to the original file when you can and not re-edit edits.
TIFF files can also be 8-bit or 16-bit. 8-bit TIFF files offer no real benefit over 8-bit JPEGs, but 16-bit TIFFs offer much smoother tonal transitions and will withstand heavy editing far better.
The TIFF format is really reserved for editing processes these days. When you send an image from Lightroom or Capture One to another program for editing, the 16-bit TIFF option will yield the best quality for the external program to work with. The only way to get a 16-bit TIFF file is from within RAW processing software. 16-bit TIFF files are large, commonly 120MB+ for an average digital camera image.
Which file format is best for shooting?
It’s a pretty simple decision because cameras really only give you two options. JPEGs are OK if you want to share images straight away with no further editing, but RAW files are best for images that you intend to edit, enhance and perfect later.
Which file format is best for editing?
If you shoot RAW with your camera and you’re using a non-destructive photo editor like Lightroom, Capture One or DxO PhotoLab, leave your images in their original RAW format. The software won’t edit the files directly but will simply store your editing instructions alongside. It will still look as if you are editing them because you will see your changes, but you will need to export a processed version as a TIFF or JPEG, say, to share with others.
If you swap images betwen programs or plug-ins while editing, 16-bit TIFF is the best option for preserving quality and editing potential, though at the cost of large file sizes. The Photoshop PSD format can serve the same purpose. You don’t have to be using Photoshop, as the PSD format is used widely amongst other software applications too.
When it comes to sharing images, the JPEG format is both effective and efficient. By the time you generate the JPEG, you will already have carried out all the tonal and color manipulations you need to, so the technical limitations of the JPEG format won’t matter and you’ll have an image file that can be viewed anywhere on any device.
