Common Image File Extensions Explained

A Collage of Common Image File TypesEach of us comes across dozens of different file types daily. They end in three or four letters and for the most part we know what to expect when we see the most common ones. While you may know to expect an image when you read .jpg or text when you see .doc or .docx, that doesn’t mean you know what these extensions mean and how best to use them. Here is a brief overview of some of the most common file extensions and some of their use cases.

.jpg or .jpeg (Joint Photographic Experts Group) – The most common file format on the web, JPGs are compressed image files. Images can be compressed to varying degrees making the file smaller but eventually adding noticeable artifacts and a grainy texture. JPGs are great for displaying photos online when perfect quality is not as important as fast load times.

.gif (Graphics Interchange Format) – One of the more limited file formats, GIFs are limited to displaying no more than 256 colors. This makes photographs and any graphic with a gradient look low quality, while images with few colors can benefit from the small file size. GIFs also allow for transparency and animation.

.png (Portable Network Graphic) – Produced as a successor to the GIF, PNGs support many more colors than the GIF extension. PNG files tend to be larger than JPEG images; however, they have the ability to incorporate transparent backgrounds. Though often larger in size than JPEGs, PNGs are useful for web designs that require transparency or where quality is a premium.

.tif or .tiff (Tagged Image File Format) – These files are commonly used by printers and photographers. They are uncompressed and therefore are going to be larger than JPGs and PNGs. TIFs are widely supported by most image editing and viewing programs but cannot be displayed by most web browsers.

.eps (Encapsulated PostScript) – This format can store both bitmap and vector graphics. The advantage of vector graphics is their infinite scalability. EPS files can be opened by nearly all illustration and graphics programs but cannot be displayed on the web. This format is best for logos or graphics that may be printed at varying sizes.

.pdf (Portable Document Format) – A file system developed by Adobe, PDFs are highly flexible and widely used. Depending on how the file is exported it can contain typefaces, layers, raster and vector files, as well as text. PDF files are capable of containing both vector and bitmap content editable by Adobe Illustrator and Photoshop.

.ai and .psd (Adobe Specific Formats) – Adobe Illustrator and Photoshop are two of the most common image manipulation programs. AI and PSD file types are the default output of these programs and store all information and settings, such as layers and masks, which have been applied to the image. While these images cannot be displayed on the web, they are good to keep around in case you ever want to edit the image in the future.

For more information on file types and when to use each, take a look at: