Common File Types and When to Use Them
File types can often seem like a coded language that only designers and developers use, but there are a few common rules that can both help you as a consumer figure out what files you need to receive from your creator and help you see the logic behind any files they are asking you for.
At the top level, there are two types of files: Raster and Vector. Raster files are those which use pixels to make up the image (or the print equivalent of dots per inch a.k.a. DPI). On the other hand Vector images are images made up of, in a broad sense, math. These files translate mathematical information into a shape and use points and curves to create an image.
A quick way to tell if an image you are viewing is Raster or Vector based is to zoom into the image as far as you can. Does the image look grainy or pixelated? Then it’s a raster image. Does the image look just as clear and crisp at 500% as it did at 100%? Then it’s probably a vector.
PhotoShop files are generally considered a “working file,” or the file that a designer will create the initial design or adjust a photo within. It is common for the designer to give a client the working files at the end of a project, and I encourage you to ask for them whenever possible. This allows you to make updates yourself if you are able, or to hire another designer if your relationship with the current designer doesn’t last.
Photoshop files are generally very large as they hold a lot more information than other raster files, and are not recommended to be used for anything other than editing. One of the other rastor file types are prefered for final pieces and for inserting within other file types.
Jpegs (or jpgs) are most commonly used for digital projects such as emails, online ads, and websites. Jpegs cannot be transparent, and are not recommended for files that you plan to re-save frequently This is because jpegs are “lossy” files. Lossy files are generally smaller file sizes, ideal for web, but they lose resolution over time as they are recompressed upon saving.
Transparency is when a file has an area without any color and can be seen through like a window. Colors can also be partially transparent, like a filtered window.
PNG files are lossless files (files that do not lose resolution when re-saved) that are commonly used for print and for digital files which require transparency. PNG files are smaller than Tiffs (see below), but larger than a jpeg. They are prefered for inserting within print pieces and for digital logo files.
Tiff, like a PNG, is a lossless file type that can have transparency and is not compressed. The major difference between PNG and Tiff is that, like a PhotoShop file, a Tiff can save layers to be edited again later. Tiff files are often used by professionals for print work, and have the largest non-photoshop file size.
Like a PhotoShop files, Illustrator files are the working files of vectors. While other vector files can be edited in illustrator or other vector editing programs, Illustrator files hold the most information. These files should not be inserted within another file and a printer will rarely want the full Illustrator file, preferring to work with the smaller EPS or PDF files.
EPS files are often the file product of an Illustrator file, and are very common for final logo files. They can be opened either in an illustration program like Illustrator, in a PDF viewer, or in a browser. This is the prefered file type for a vector image that is being inserted within another file. Often designers will request an EPS of your company’s logo, so having one on file is always a good idea.
PDFs are not necessarily vectors, as they can simply be images saved in a PDF format, but often print files are saved as PDFs to be sent to the printer and client. These PDFs can include printing information such as crop marks, embedded fonts and colors, and bleeds. Most printers prefer to work from a PDF. There are also many other features that a PDF can offer, such as fillable form fields and locked files.
An SVG is essentially a digital EPS. When you want to use a graphic on a website, such as a logo, but aren’t sure what size you want it to be a SVG can be a good option, however they are not the standard. An SVG is also easy to view in your browser, where other file types may be difficult for a client to open on their end.