This is a question I get a lot as a graphic designer and it’s quite an important one. It can certainly make a difference to quality – especially when it comes to logo files. Why? Let me explain what each file does.
A raster file is composed of a number of pixels with various colours that form an image. Common file types for raster files include .jpeg, .gif & .png. The amount of pixels in an image (resolution/dpi) determines the quality of the image and also how large you can print & view the image without losing quality. For this reason, you cannot scale up a raster image without losing quality – often images that have been scaled beyond their limits are seen as “blocky” or “pixelated”.
A vector file is made up of paths or lines that can be curved and straight. Common file types are .eps and .AI (Illustrator). As these file are made up of paths and lines, they can be scaled infinitely without losing any quality. For this reason, when you’re dealing with a graphic designer, it is always best to provide them with a vector file (.eps or .ai) of your logo. By doing so you are ensuring that you are giving the the best quality file version of your logo and they will not have problems applying your logo to the artwork they are working on for you.
When you engage with cheaper or inexperienced designers for your logo design, you may end up with only a raster file and not a vector file for you logo. I often have clients come to me with only a raster file for their logo and they end up requiring a complete redo for their design. ALL PROFESSIONAL DESIGNERS WILL PROVIDE YOU WITH YOUR LOGO IN VECTOR AND RASTER FILES.
See below an example of two versions of my logo. One is a low res raster file and one is a vector file. Both are scaled to the same size but, as you can see, the raster file is pixelated and poor quality. This is because the raster file was smaller to start with and could not size up without losing quality.