In this article, we explain the differences between common image file types like JPGs, PNGs, and PDFs, their pros/cons, and the best scenarios for using them. We also go over lossy vs. lossless compression, and raster vs. vector images. Lossy/lossless refers to an image’s decompression process—lossy decompression decreases a file’s quality over time, while lossless does not. Raster images are best for photos as well as images with irregular borders, and they can be lossy or lossless. Vector images are always lossless and are best for when you need scalability.
Whether you’re a small business owner running a local coffee shop or the head of marketing for the next big start-up, there’s a good chance you’re going to have a design need at some point. Whatever that need is—a new logo, social media ad, or something else—you’ll inevitably be exposed to a vast world of file types and terms you may or may not have heard before. You probably know what a JPG is and you’ve likely heard of a vector file, but how much do you really understand them?
To reduce that ambiguity, we’d like to give you a brief overview of the most common image file types and what makes them unique. In doing so, this article will help you ensure that: 1) you are able to determine whether or not you’re receiving the right types of files when working with a designer or an agency, 2) you know what types of files to share with printers, embroiders, sign makers, etc., and 3) you are able to utilize the correct file types when working digitally, thus maximizing the quality and efficiency of your digital endeavors.
Before we go over the various types of image files, it’s important that you know what lossy and lossless compression are.
When a file is saved, it will be compressed in one way or another. When the recipient opens that file, it is then decompressed. That process will go in one of two ways: lossy or lossless. Being aware of these two types of files will help you understand the differences between JPGs and PDFs, and why one type of file is better than another for certain situations.
A lossy file won’t restore an image to its original state during decompression and the more it’s compressed, the more you’ll see a reduction in quality. That’s not necessarily a bad thing, though. Lossy compression gets rid of a file’s fine details, so the majority of people won’t even realize something’s changed (at first, at least—the effects of lossy become more pronounced with each concurrent save tha occurs). The benefit of this is that lossy files can be significantly reduced in size—meaning they’re much easier to access than their lossless counterparts.
Stick with lossy if you’re sharing images or audio/visual files, or in situations where file size is important.
On the other hand, lossless compression does restore file data to its original state. So, unlike lossy files, a file that’s lossless won’t lose any quality no matter how many times it’s compressed. This means a lossless file never loses a single bit of data—its most minute, unnoticeable parts are preserved. Don’t swear exclusively by lossless just yet, though! It does have one drawback. Because every part of the file is preserved, lossless files are much larger in size and will take longer to access, especially when sharing via email or on your website. Larger file size is not a big deal for designers, but may impact your customers or prospects.
Go with lossless if you’re working with text, or you have images and sound that require unparalleled quality.
When it comes to image files that you are most likely to see, they fall into one of two categories: raster or vector. To the naked eye, it may seem like there’s little-to-no difference between the two. However when you look a bit closer, you realize how different they truly are.
Raster files are graphics that are made up of a grid of pixels. That grid is called a “bitmap,” which is why raster files are commonly referred to as “bitmap images.” Raster files are normally used for photos, detailed graphics, or scanned images due to the fact that raster images do a much better job of displaying ranges of color, undefined shapes and more complex imagery than vector files. Raster files can be resized, but they will lose image quality when they are made larger than the original file. Therefore, always make sure your original raster file is as large as possible, so subsequent uses of the file won’t risk major quality degradation.
Short for “Joint Photographic Experts Group,” these file types are definitely the most common on the Internet. JPGs are great for images that have a wide spectrum of color being used, so you will most likely see photographs being saved as JPGs. The one drawback to JPGs, however, is that every time you save one, the image undergoes a compression algorithm that reduces the size of the file. In doing so, the image quality decreases each time it’s saved. This is a great example of “lossy” compression.
“Portable Network Graphics,” PNGs are also one of the most common file types you will come across. Although they are also good for photographs, the main selling point of the PNG is the ability to have a transparent background. So, most icons you see online or graphics that have irregular borders are most likely the PNG format. Unlike JPG files, PNGs allow for “lossless” compression, which means that the quality of the image will not decrease each time the file is saved. In other words, PNGs are a bit more scalable than JPGs, but not remotely as scalable as vector files.
On the other end of the file type spectrum is the vector file. As opposed to raster images, which are made up of a grid of pixels, vector files are made up of individual points and paths. Because of this, vector files are extremely scalable, meaning they can be made much larger or smaller than the original without degrading the image quality. Vector files are commonly used for logos, icons and other types of images that require scalability. By their very nature, vector files are lossless, so you should stick with these types of files when quality is necessary.
Yes, although you normally see PDFs as large word documents, at their core, they’re a graphic file. Originally known as the “portable document format,” PDFs were invented by Adobe, who wanted to be able to capture and review rich information on any device. Extremely versatile, PDFs are most commonly used by people needing to share production artwork.
SVGs, or “scalable vector graphics,” are simple, plain-text files that describe lines, curves, shapes, colors and text. Based on XML, SVGs are mostly used to display a variety of graphics on the Internet and in other places. SVGs have a level of versatility and flexibility that few file types can match. Consequently, they’re very popular for creating images that require interactivity and/or animation.
“Encapsulated postscript” files, EPS was designed for producing high-resolution graphics meant for print. The versatility of the EPS file format is derived from its status as a “universal file type.” This means that just about any design editing software can open and utilize it, perfect for when you don’t know what type of software someone else uses.
There is so much more to image files than what meets the eye—each type has its own functionality and optimal scenario for use. At this point, you should have a better understanding of the different types available to you, when you should use them, and how compression/decompression affects them. Now, when your social media manager wants to upload the latest team picture, you’ll be sure to send the JPG version, and the next time you have a brochure to send to your printer, you’ll know to stick with the PDF your designer sent to you.
The world of file types is can be incredibly complex, but having a basic understanding of how it works can make the difference between this: