Common Image Files Types & When to Use Them

By January 21, 2016 Design

Not everyone is a designer, so it’s understandable why image types and file extensions can cause confusion.

To help you better understand some of the most common file types (and when and where they should be used), we’ve created a quick cheat sheet for reference.

HIGH-RESOLUTION V. LOW-RESOLUTION

This is a common conversation we have with clients when discussing images used in print and web. We’re sure you’ve heard the term DPI. So, what’s the difference between high-resolution and low-resolution files, and why does it matter?

  • DPI stands for dots per inch
  • The dots are units of measurement that determine the density of dots (or pixels) in an image
  • The number of dots per inch determine if an image is appropriate for web or print

DPI BREAKDOWNS

Here’s an easy breakdown:

  • 72 DPI (or anything lower) is low-resolution and should only be used for web
  • 300 DPI (or anything higher) is high-resolution and can be used for print. High-resolution can also be used for web, but should be sized down, as images this heavy can weigh down a website.

Often times, people hear that an image is 72 DPI and they need it for print, which has a minimum requirement of 300 DPI, and they try to ‘trick’ the system by changing the DPI. While this would be an easy fix, it does not work that way. Adding dots to a low-resolution image will result in it rendering grainy (looking horrible) in print.

FILE TYPES/EXTENSIONS:  WHEN AND WHERE TO — USE THEM

JPG / JPEG
JPEGs are known for their “lossy” compression, meaning that the quality of the image decreases as the file size decreases. Paying attention to the resolution and file size with JPEGs is essential in order to produce a nice looking project. JPGs are most commonly used for print projects and adding images to Microsoft Office documents.

PNG
PNGs are perfect for interactive documents such as web pages, but are not suitable for print. While PNGs are “lossless,” meaning you can edit them and not lose quality, they are still low-resolution. They are also popular for web projects because you can save images with more colors on a transparent background, creating a much sharper, web-quality image.

GIF
GIF files are typically animated files that may be used in banner ads or social channels. GIFs are a common file type for web-based usage when an image needs to load quickly.  

PDF
PDF stands for portable document format and were ‘invented’ by Adobe. PDFs are very popular when assembling files created in a variety of file types, as they preserve all elements of the original document. PDFs should be be ‘optimized’ if you plan to use them online, as they can become very heavy if they include a lot of images or graphics. This is extremely helpful if you’re sending a project to a printer, colleague or client. Anyone can view a PDF file if they have Adobe Reader, which is free.

PSD
PSD files are created and saved in Adobe Photoshop. These files contain ‘layers’ that assist designers in creating and modifying the image seamlessly. You will often hear people reference a ‘native’ file. A PSD is an example of this, since it is the original format in which the file was created. Be aware: if you do not have Photoshop on your computer, you will not be able to open or modify a native PSD file.

AI
AI is the image format preferred by designers when they are creating artwork from scratch. This file type is not typically used by non-designers, as it’s purpose is to create artwork and/or edit existing artwork. In addition, one must have Adobe Illustrator software to access this file type. If you need help with editing artwork, you’ll most likely want to reach out to your graphic designer for assistance.

INDD
An INDD file is a native file created in InDesign – a commonly used design program for newspapers, eBooks and brochures. This file type is not typically used by non-designers, as it’s purpose is to create artwork and/or edit existing artwork.

While there are many more file types out there, we hope this guide helps you feel a bit more comfortable with these terms!

Leave a Reply