Raster? Vector? Pixels? What???
We’ve all had that moment at some point in life. A time when you needed a quick clip-art on a flyer so you ran over to Google, copied and pasted something into your document, sent it to the printer and bam, blurry mess. It looked okay on the screen, so why didn’t it print well? Here’s where knowing the difference between raster images and vectors is important. I’ve found myself explaining this concept on a regular basis lately so I’m hoping a quick rundown will help you determine what you need for what kind of projects.
First, let’s talk about raster images. The everyday images and graphics you post and use are typically raster images. You usually see these in a JPEG or PNG file format. They’re made up of pixel grids, also called bitmaps. If you open them in a photo viewer on your computer and zoom in close, you can see these individual pixels. While raster files can typically be scaled down and retain their quality, enlarging them causes the pixilated effect that makes them blurry. While higher resolution files help, there will always be size limitations to what you can do with raster images.
As for vectors, they’re not your everyday file type. You’ll commonly see these files shared in an EPS (encapsulated post script) format or an SVG (scalable vector graphic). Depending on your computer and operating system, you may not be able to open an EPS file without a vector based software like Adobe Illustrator or CorelDRAW but SVG images will open in an internet browser. Where raster images are made of pixels, vectors are made of paths (lines). You can zoom in on one of these files and never see a change in the quality. Because of this, there are no limitations on resizing a vector.
Let’s talk some real world application now. At LHD this difference is important when it comes to cutting decals. Our vinyl cutter can only read paths, it can’t define pixel edges, therefore we have to have vector files to cut. Only have a JPEG? Not a problem, we can convert it to a vector via a trace function in our software. However, the quality of that conversion is based on the quality of the raster file. The lower resolution the file, the rougher the trace comes out. This is where you get into some setup fees with different companies as they have to manipulate or even rebuild your design into something usable.
This is also applicable in the world of logo design. Anytime you’re paying graphic artist for a logo, make sure you get a vector file for that logo, you’ll need it. If the person asks, “What’s a vector?” find another designer. Most designers will create the logo as a vector file then save you raster versions as well. Don’t be afraid to ask a designer what software they’ll be using to make your logo. If it’s Adobe Illustrator or CorelDRAW like I mentioned above, you’re in great shape. If it’s Adobe Photoshop, it’s still okay, just make sure they’ve got a way to get you vector art. Make sure you’re getting your money’s worth out of that investment. Remember also that there are exceptions to every rule and there may be pieces of your logo (like when a photo has been incorporated) that can’t be sent in vector format.
There is so much more that goes into these two file types and when to use each but I hope covering the basics helps you understand why different files work the way they do. If you ever had questions, feel free to contact me and I’ll be happy to help you sort out the world of raster and vector files.