Vector files: Useful in many different environments.
When you’re working digitally, there are two kinds of image file types: raster and vector. Both image types may be saved with several different file extensions. It’s important to understand when to use each image type and the best file extension for particular situations.
What is a vector image?
Vector files are images that are built by mathematical formulas that establish points on a grid. Raster files are composed of the colored blocks commonly referred to as pixels. Because they can infinitely adjust in size without losing resolution, vector files are more versatile for certain types of tasks than raster files. The most common types of vector files are:
.ai: Short for Adobe Illustrator, this file is commonly used in print media and digital graphics, such as logos.
.eps: Encapsulated PostScript is an older type of vector graphics file. .eps files don’t support transparency in the way more modern file formats like .ai do.
.pdf: The Portable Document Format is built for the exchange of documents across platforms and is editable in Adobe Acrobat.
.svg: The Scalable Vector Graphics format is based in XML (a markup language used widely across the Internet that's readable by both machines and humans). It’s useful for the web, where it can be indexed, searched, and scripted.
It’s worth remembering that there are different resolution requirements for web or print – and this may affect how large your vector file needs to be.
The ideal image resolution for web is 72 dots per inch (dpi). Any larger and the images will take too long to load. This is a much lower resolution than what would be recommended for print, which would be at least 1600 x 1200 pixels for a 16x12-inch print.
What is a raster file?
Raster files are composed of coloured blocks commonly referred to as pixels. Comprising a fixed number of pixels, raster images can’t be resized significantly without losing some of their resolution quality. Images distort and become grainy when stretched to fill a larger space, which is why they can appear pixelated when resized. Common types of raster files include:
.jpg: A compressed image format standardised by the Joint Photographic Experts Group (JPEG). This is the most commonly used format for digital and online photos.
.png: Images saved in the Portable Network Graphic (PNG) format have the ability to display transparent backgrounds.
.gif: The Graphic Interchange Format (GIF) file extension is used for animated graphics. This is the second-most used image format online.
.tif: Images saved as a Tagged Image Format File (also TIFF) are popular with photographers and graphic designers as they can be edited and re-saved without losing image quality.