So, raster vs vector? You may have heard of them and just nod politely when they are mentioned. But, what do they actually mean and how are they different?
Raster images
A raster image (also known as bitmap) is made up of individual pixels and each of those pixels contributes to the overall image. This means raster images are capable of rendering complex, multi-coloured visuals, such as photographs. JPG, GIF and PNG are all examples of different types of raster files.
Quality of a raster image is often dictated by the dpi (dots per inch) and the overall dimensions of the image. The greater the dpi and dimensions, the higher the quality, and often the file size. They cannot be scaled without sacrificing quality. For digital deliverables a 72dpi is sufficient whereas print requires a minimum of 300dpi.
Vector images
Vector images are made up of points, lines, and curves that are based upon mathematical equations, rather than pixels. Often containing less detail than a raster image, a vector will retain appearance regardless of size and can be scaled infinitely.
Although you can include gradients and shadows in a vector, a true vector graphic is comprised of line art that is filled with colour.
SVG, EPS, PDF and AI are common file formats for vector graphics. Because the scaling versatility, vectors are excellent for logos, illustrations, sign writing and embroidery.
When should you use a raster or vector?
Raster images should be used for photos while vectors should be used for logos and illustrations. If something requires more detail at an adequate scale, raster images are optimum. However, vectors should be used at radical scale or for clarity of defined edges in simple shapes, such as logos and illustrations. See the basic examples below.
| Raster Example | Vector Example |
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The above examples demonstrate how a raster image handles gradients and depth better than a vectored image.
| Raster Example | Vector Example |
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The above logos have been scaled larger than their original file format. The raster image loses quality the larger it is made, whereas the vectored image retains its smooth outlines and block colour.
So, raster vs vector? It is important to consider purpose, context and scale when deciding whether to use a raster or vectored image. You can find out more about these file types in out file format blog.
