Between Lightroom and Photoshop, we see quite a range of file types - from our original RAW files, to TIFF, JPEG and PNG.
If you are wondering about the characteristics of each file type, and when you should use them, this post will get your started.
Below is a list of some of the most common file types found in photo editing including the abbreviation, file name, and its characteristics.
These files are produced in your camera. They are considered lossless, which means that they are not compressed in any way and give you the maximum amount of information within the file. They require conversion to be edited, and are not viewable within an internet browser (for example you cannot upload a RAW image file to Facebook).
DNG - DIGITAL NEGATIVE
After importing your RAW files onto your computer, Lightroom allows you to then export your image as a DNG. While still considered a "RAW" file format because they are lossless, DNG's are quite smaller than RAW files. Once converted from RAW to DNG, the file can be read with any type of software that supports the DNG format.
DNG is also the proprietary file format of Adobe. When you shoot in RAW, your image file contains information that is unique to your camera's manufacturer. Converting your RAW file to a DNG makes the file more universal, therefore more usable across Adobe software.
PSD - PHOTOSHOP FORMAT
Both Lightroom and Photoshop support this type of file format, which is extremely useful if you edit in both Lightroom and Photoshop. The PSD format, in Photoshop, allows you to work with layers, but can also be manipulated in Lightroom (though LR doesn't have layers, you can still edit the PSD in LR) and brought back in to Photoshop with the layers intact.
JPEG - JOINT PHOTOGRAPHIC EXPERTS GROUP
JPEG's are a compressed, "lossy" file format that are great for sharing online or through email/text. They do not contain as much information as RAW or DNG files, therefore they are not considered the best file format for editing, but they are extremely handy for quick viewing/sharing and for that reason are one of the most common file types.
TIFF - TAGGED IMAGE FILE FORMAT
TIFF's are slightly larger than JPEG files, can be either compressed or uncompressed, and are a standard file format among printers. While most print labs will accept only JPEG's, some print labs will recommend sending TIFF's for printing.
PNG - PORTABLE NETWORK GRAPHICS
This particular file format is often used by graphic designers, because the format lends itself to producing the most detail within solid colors. Photographers often use this format for uploading their images to Facebook and other social media outlets. Since PNG's tend to run a bit larger than JPEG's, though, make sure that, when you upload to Facebook, your PNG is under 1 MB, otherwise you may run into some pixelation issues.
So, when should you use each particular file format? Well, a lot of that is up to you and your personal preferences/needs. I am not someone who swears by one method over the other in a given situation, but I do think it is helpful to know the guidelines. Here is a very loose, general rule of thumb:
For Sharing Online