Raster vs Vector
Two very common terms heard in the design industry are vector and raster images, but what does that really mean? We now know the difference between the different files types such as jpg, eps and png, but lets take a closer look at what makes a vector or raster image. The base of a vector images is relatively confusing to explain, if you were to sum it up it would be that it is a mathematical formula that uses points, lines, curves and shapes. Essentially vectors are made up of paths.
The great thing about vectors is that they can perfectly scale. Whether you are making the image large or small your edges will be clear and smooth, which is ideal for logos. How do you make vector graphics? Typically you will create your graphic in a program like Adobe Illustrator. You can make simple to complex drawings using shapes and colours.
As vectors are made of paths you can edit the shapes by using points to adjust the direction, you can also add masks, strokes or fill the shape with colour. Each shape that you create will become a layer that can be merged or grouped. Illustrator has come a long way to provide effects similar to Photoshop, where you can use features such as drop shadows and even trace rasterized images into vector. Once you are ready to save your file, there are two main formats used, .eps and .ai. Both of these will provide the user with a quality scalable graphic, which works for print and web and is ideal format for logos.
A rasterized graphic is made up of a grid of pixels; tiny blocks of information that together form an image. This grid is also known as a bitmap and makes up file formats such as jpg’s and gif’s. As the images are made of pixels they cannot stretch or resize the same way that the mathematical vectors do. Users will find issues with the clarity of details and lines.
Why should I use raster images? Raster images are the main format of digital photographs, they are excellent in accurately demonstrating image details. Commonly worked on in Adobe Photoshop images can be edited in amazing ways, from hues and colours to white balance, blemish touch ups and photo repair Photoshop can do it all. Edits can be made to rasterized images using multiple layers, each time you create a layer and make your adjustments, the original images will remain untouched, which makes it easy to undo possible errors made during photo enhancements.
Another important factor would be saving your image for the proper output. Web space often favors an image closer to 72 dpi (dots per inch) versus print, which would require 300 dpi. Printing an image at 300 dpi will allow for a higher quality print.
In summary, because vector-based images are not made up of a specific number of dots, they can be scaled to a larger size and not lose any image quality. If you blow up a raster graphic (the opposite of vector - jpg, png, etc), it will look pixelated and blurry as it gets larger. When you blow up a vector graphic, the edges of each object within the graphic stay smooth and clean because it's using "math" to produce new data to fill in what would be pixels or dots in a raster.
This makes vector graphics ideal for logos, which can be small enough to appear on a business card, but can also be scaled to fill a billboard. Common types of vector graphics include Adobe Illustrator and EPS files. Think of a raster graphic as a tiny photo you try to enlarge on a photocopier. The larger it gets, the blurrier it becomes making it look like a bunch of dots on paper. A vector, in contrast, allows you to enlarge the image infinitely without losing its clarity.