As a designer at a marketing company, I spend a lot of my time thinking about file formats. JPEGs, PNGs, EPSs, AIs, MP4s, WEBMs – there’s no limit to how many different file formats there are for saving data, be it images, video, audio, text – anything!
Most people aren’t familiar with different file formats or what the differences are between them, and for the most part, they shouldn’t really have to be. Our computers and their operating systems do their best to hide as much of the nitty-gritty of how the work we’re doing is getting processed. We shouldn’t be concerned with how the computer stores the data we are accessing. Let us focus on the work we’re trying to get done!
But let’s say you’re doing some work that requires you to know the difference between all these acronyms at the ends of file names. Maybe you’re sending your logo to a manufacturer to get custom made signs or shirts, or you’re trying to upload your profile image to a social media account. Which files should you use and when? If a printer asks for a PDF, does it really matter if you send a JPEG instead?
At Muse, we provide our clients with their shiny new logos in a few different, commonly used file formats because they have specific use cases. We could get all technical and really dig down into the history and minutiae behind the differences between these files, but I’d rather go over the fundamental differences between some common image file types and discuss why you’d use one over the other (maybe with a little minutiae here and there).
PNG (sometimes pronounced “PING” by excitable folks) stands for Portable Network Graphics – but even that might be too much information. The PNG format was developed to replace another file type you might have heard of called a GIF (pronounced “JIFF” with a soft G sound by people who want to annoy the people who pronounce it “GIF” with a hard G sound, who pronounce it that way to annoy the soft-J people). GIFs were designed as a compact image file format that could be shared easily on the web. But since they were developed in the early days of the internet, they are a little primitive – they don’t support many colours, and can get quite large, meaning they load slower on web pages.
PNGs are a great, versatile update to the GIF format and have become the standard graphical format for images on the web. PNGs support a wide colour gamut. They can show lots of different colours so you don’t get any weird pixelation in gradients. And they use a lossless compression format that, in really simple terms, means you can compress images with smooth lines without them getting all jagged and nasty looking. That means they’re great for logos or typography!
Maybe most importantly, though, PNGs have what is called an alpha channel. The alpha channel, along with the colour channels in the image file (the red, green and blue channels in a file combine to make a full-colour RGB image), contains information about transparency. Say your logo is a circle with some type and you want to put it on an image without a white box showing up around it. PNGs have data baked into the file that tells the computer “this part is see-through, this part is red” so your background content can show through parts of your PNG.
If PNGs are so great, why would anyone ever use a JPEG? JPEGs (also written as JPG, and pronounced “jay-peg”, but never really pronounced “jay-pee-jee”) may be one of the most ubiquitous file formats ever. They’re like the MP3 of pictures, and something they do incredibly well is compress large, complex images (like a photograph or a painting, with lots of colours and visual information) to a manageable size without sacrificing too much legibility (as long as it’s viewed at the intended size). JPEGs don’t contain an alpha channel, so if you have a JPEG of your logo on a white background and pop it on top of a photo, you’ll have a big white box around your logo and nothing will show through it.
Another limitation of JPEGs is the very thing that makes them so useful – compression. JPEGs are great for making a big image smaller so it loads quickly and doesn’t use up too much storage, but they aren’t good at getting bigger. If you try to blow up the scale of a JPEG, you start to see all the pixels that make up the image at its specific size, which we’d describe as looking pixelated, blurry or low-resolution.
So JPEGs are great for making complicated images smaller, but not for using in large printing applications or for anything that should contain transparency information. One important thing to remember about JPEGs is that they are nearly universally compatible with software. If you want to send a file to someone and guarantee they’ll be able to open it, you’ll be safe sending a JPEG.
Vector Files (EPS, AI, and more!)
Up to this point the files we’ve been talking about are known as rasterized image files. This means the images are all pixel-based. The image itself is actually “drawn” by arranging hundreds and thousands of little squares of colour that, when viewed as a whole, make up an image.
But there’s an entirely different way that a computer can store information to “draw” an image on a screen – they’re called vectors.
EPS (Encapsulated PostScript, maybe the most boring sounding file name of all), AI (Adobe Illustrator, a proprietary format based on the Illustrator application by Adobe) and SVG (Scalable Vector Graphics) files are all types of vector-based image files. The difference between a vector file and a raster file is that, instead of storing pixel-based information to make up an image, vector files store mathematical data about point coordinates and how lines connect them. The computer uses this information to figure out how a shape is drawn, regardless of size. This makes vector files super versatile. You can scale a vector image that’s one centimeter wide to one kilometer wide if you need to, and it would be just as clear as when you started. All you’re really doing is saying “I have a line drawn at this angle between these two points” – no matter how far apart those points are, their relationship stays the same!
Not all software can read vector files, but many manufacturers and graphics companies will request them to work with since they’re so versatile. You can’t really make a photograph into a vector file, since it’s too complicated to convert into point-line data, so we reserve this file type for graphics and artwork.
And now you’ve met three types of image files, and know them well enough to know when to use one over the other! The truth is that, as long as if you hit “print” or “send” and you get the result you wanted at the other end, it doesn’t really matter what file type you use. This information is for when you start to run into trouble with your files – why can’t I upload an EPS of my logo as my LinkedIn profile? Why did this print of my logo turn out so pixelated? Knowing the right file to use from the start can save you a headache and make sure you’re creating great looking work.