Raster Images vs. Vector Graphics
July 13, 2011 1 Comment
Graphic Design students should be aware of the two main different types of Graphics that designers work with on a day-to-day basis. These main categories are raster and vector graphics. Each type of graphics is used for different types of projects. If we where to download the images posted below this post we would have three raster graphics as .jpg formats and three vector graphics in .eps or .ai formats. Furthermore, if we where to open the downloaded graphics with the appropriate software application (Photoshop and Illustrator) and zoom in as much as possible on each image, we would see clearly one difference between both types of graphics.
The main difference between raster graphics and vector graphics is that raster graphics are composed of a set amount of pixels, or small squares of different colors. On the other hand, vector graphics are composed of mathematically calculated lines or paths and anchor points that define each shape or object. This main difference makes raster graphics unable to be enlarged too much, because they loose quality and become pixilated, meaning that the more we try to enlarge a raster graphic the less quality it will have. On the other hand, vector graphics can be scaled as much as you wish either enlarging or shrinking the graphic. This is the main reason why logos, along with other types of graphics should always be created using a vector based software application such as Illustrator.
Another difference between the both is that it is very easy to convert a vector graphic into a raster graphic. However, converting a raster graphic into a vector graphic requires advanced software skills and the image is ultimately not visually equal to the original raster graphic, but instead it is a vector version of it. Some raster images are too difficult to convert to vector, so it could also be impossible to do so for some images. The conversion of vector into raster is as simple as selecting the “Export” option inside Illustrator and selecting the JPG format. Converting a raster image into a vector version requires placing the image as a raster linked file into Illustrator and manually “tracing it” using the pen, pencil or brush tools. Ultimately, the vector version of a raster image does not look exactly the same as the raster version, and a raster version of a vector graphic looks just like the vector graphic.
Another important difference, especially when it comes to designing logos and icons, is the transparency and shape restrictions. When you create a raster image it will always be within a rectangular shaped canvas. Even if you save the raster image as a PNG file format with a transparent background, you will have an “invisible” rectangular background behind it. On the other hand, when you save an irregularly shaped design from a vector based application software, the image will be the shape of the object and it will have no background, not even an invisible background.