Updated August 2016
There are so many different file formats when it comes to photography. Compressed and uncompressed formats, RAW and editable formats, the list goes on. In this article, I’m going to talk about the most common file formats for photographers, explain what they do and why we might use them.
JPG PNG RAW DNG PSD TIFF XMP
JPG (jay-peg) is a lossy (means 'compressed') format and is the most common file format. There’s two versions of the JPG, .jpg and .jpeg. JPEG stands for Joint Photographic Experts Group–who you might have guessed–were a group that created the JPG standard. It’s a lossy format that your images would be saved to when they’re finalised. You use a JPG for all your final images when saving or outputting from Photoshop or Lightroom. Every program and device can read JPGs and it's the safest file type to use.
PNG (ping) is a lossless (means 'uncompressed') format and is used more in the graphic design community than photographic. PNG stands for Portable Network Graphic. It’s popular among designers as it allows you to preserve transparency in a graphic. This is great for logos for example. Photographers can use it however, but more so on their website as the png format isn’t suited for photography. Photographers would save their logo or watermark as a PNG to enable them to use it on their photos without a distracting white box.
RAW format is the digital equivalent to the film negative. In Canon cameras, the RAW format is .CR2, .NEF in Nikon, .ORF for Olympus and .AWR for Sony. Your camera can shoot straight to JPG, but that’s like the equivalent of shooting polaroid. Once the image pops out, you can’t really do anything with it. But RAW is like shooting film. You’ve got an entire image there to play with before it’s finalised.
Have a look at the comparison below. These images were shot without a lens, and the camera’s body cap left on. This is so the sensor captured literally nothing. On the left is a JPG, with the exposure pushed to 100% in Lightroom. On the right, is the RAW file with the exposure pushed to max. You can click the images to enlarge them.
You can see that the JPG has ugly colour splotching and the noise is rather harsh. The RAW on the other hand, is a lot smoother. The noise is consistent in colour and is more fine. The RAW’s noise can easily be fixed and removed from images. But the JPG’s noise is all but lost. Obviously, in a normal image the noise wouldn’t be this crazy, but you’re going to notice the noise in JPG images far more than in RAW. That’s why we shoot RAW… Among a lot of other reasons of course.
XMP files are known as sidecar files. These files are created when changes are made to a RAW file. What happens is the adjustments and changes you make to a RAW file get saved to a sidecar file (the .xmp) instead of being saved to the RAW file itself. This prevents you from losing the original untouched RAW file. These XMP files do take up space on your hard drive and are incredibly important. If you ever see these files next to a RAW file... don’t delete it. If you do, all the adjustments you’ve made to the corresponding RAW file will be lost.
DNG is another RAW format, however it’s not a propriety camera RAW format, instead it’s a software RAW format. Adobe created the .dng raw format in the hopes it would become the standard in RAW formats. DNG offers the maximum compatibility between Adobe programs and doesn’t have the extra baggage of XMP files. All changes made to DNG RAW files are saved inside the DNG file itself. This prevents you from having extra files taking up storage space, and DNG files are generally smaller than the RAWs so that's a bonus.
The downside are the changes are saved to the file. So you can run the risk of losing the full uncompressed RAW data.
PSD stands for Photoshop Document. This is the propriety file format for saving Photoshop documents. They are uncompressed files containing all metadata, layers, data etc. which enables you to open them and continue working on them. Saving your Photoshop work as .psd is the best way and has the most compatibility for future versions of Photoshop.
A TIFF file is similar to a PSD in that it can retain layers and can be uncompressed. However, TIFF isn’t a proprietary file format for any one program. A lot of print labs will ask for your files in TIFF format as they are capable of offering everything a JPG image can, though without any compression and without the need to open a PSD and convert to another format.