Vector and Raster are words that are thrown around a lot in design. In essence they are two distinct types of image, but knowing which one to use in any given situation is vital. Here is the Printworks Online guide to Vector vs Raster images.
What’s the Difference?
The difference between these two image types is the way that they are made up. Raster images consist of a series of dots/pixels that together build up the image. They are what most people are familiar with, and if you’ve ever zoomed into an image and seen a ‘pixelated’ appearance, then you’re looking at a raster.
Vectors on the other hand are made up of a series of lines and fill colours, as apposed to pixels. Therefore, they can be infinitely scaled up or down. In essence you could zoom into a Vector as far as you can go, and all the elements will still stay crisp and sharp.
Pros and Cons?
Raster files can have a large amount of complex detail due their pixel-based nature. However this does increase the file size and means they cannot be scaled or resized easily, without a reduction in the quality of the image.
Vector files can be scaled up or down infinitely, and the way that the file is structured makes them much smaller in size than raster images. However, as they are made up of lines and fills the images are less detailed.
This image shows you the difference in clarity between raster and vector images. (It is only an example however, as ironically the image above had to be raster-based for the web.)
When to use them?
All photographs are raster images. The dot-based nature of raster files mean they can allow for a photographs complexity.
As you can see from this magnified section, the raster image cannot be enlarged as it creates a fuzzy distortion. However when viewed at the correct size (the main image) it appears completely sharp to the eye. This kind of detail, as seen in photographs, cannot be replicated in vector form.
Logos should always be created as vector files. At a later stage, the images may need to be converted to raster for certain uses such as on the web, but vector files should always be used as the main file. This is because they can be scaled up and down to cover all possible uses of the logo.
For digital illustrations, vectors should always be used to keep the graphics crisp and scalable.
Images on the web are raster, as by their nature websites are viewed on pixel-based screens. All images should be converted to raster copies and saved as the appropriate resolution for use on the web.
Any text involved with a design should be saved in a vector format. You can always combine text and raster in designs such as business cards, but the text should never be saved as raster as it will pixelate and become difficult to read at small sizes.
For large format graphics it is always best to use vector images to allow for images to be scaled without loss of quality, and to keep the file sizes relatively small and easy to use. Sometimes photographs (so raster) are needed, but make sure they are big enough to stay at a decent quality, and be aware that the file size will be a lot larger.
Adobe Creative Suite is the design standard for image creation so I will use it as a basis for the following suggestions:
Photoshop is raster-based, so is only suitable for photograph manipulation and the conversion of vector images to raster copies for web and screen applications.
As vector software, Illustrator should be used to create vector images, and for resizing vectors.
Indesign is a program that allows you to combine various raster and vector images in one document. The software is perfect for text reliant documents, for example our online business cards.
Follow these simple rules with your images and documents to make sure you always end up with the highest quality results.