In graphic design, you will encounter two different types of images: raster and vector. What is the difference between them, and when do you use each format? Whether you’re a new designer, a seasoned pro, or someone looking to hire a designer, it’s important to know when and how to use each image type as well as their advantages and disadvantages. By looking at the nuances between raster and vector images, I’ll help you decide which format fits your project.

Raster Images

Raster images are made up of pixels arranged on a static grid. A pixel is a square of solid color made from the combination of red, green, and blue light. One way of thinking of a raster image is to picture it as a mosaic. Up close (zoomed in), it may appear as just a series of squares, but from farther away, an image forms. Because the pixels are designated to a space on the grid, raster images are resolution-dependent. In other words, the number of pixels is fixed, so images cannot be resized without distortion. More pixels mean higher quality, higher resolution, and a larger image (which results, subsequently, in a larger file size). 

Though you are limited with the scalability of a raster image, the biggest advantage of this image type is that it can hold a large amount of color information. Raster images are ideal when you want to show the subtleties of color and shading. Projects best suited for raster images include photography, illustration, and other designs intended for electronic use. 

Vector Images

Unlike raster images, vector images are infinitely scalable. This is because these images are made out of mathematically calculated paths instead of fixed pixels. Essentially, vectors are geometric shapes that can be stretched and manipulated as need be.  A vector image is comprised of three elements: points, polylines, and polygons. The simplest of the three is the point. Several points connected together form a polyline, also known as a path. A designer can assign color, stroke weight, and other attributes to the paths. When all points are connected by a path in a closed shape, this forms a polygon. 

While the mathematical component of vectors prioritize crisp, precise lines, it can be difficult to replicate an imperfect, hand-drawn look with this type of image. Furthermore, vectors do not display complex color gradients, textures, or shading, so your work can result in a flatter, more cartoonish style. Vectors are best suited for logo designs, packaging, or anything that’s intended for print. 

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