What are the differences between vector graphics and raster graphics?
I understand from prior knowledge that there are two different image format / composition options available for creating images; raster and vector.
I would like to understand more about them, such as what the defining characteristics of each are, and what typical, generic use-cases each might have.
What are raster graphics composed of?
- When would I want to choose raster over vector?
What are vector graphics composed of?
- When would I want to choose vector over raster?
Vector graphics are graphics in which the image is represented in a mathematical fashion. What this allows one to do is to zoom in an image to infinite precision. They are ideal for situations in which an image might be used at various resolutions and dimensions.
Raster graphics are of a fixed dimension, somewhat like a grid pattern with specified values at each point. These graphics are the default for things from the real world (IE, scanned images, photographs, etc). They are ideal for use when an image will only be used once, and will never need to be enlarged, or if portions are coming from a photograph or other real-world image.
(that's Illustrator on the left, Photoshop on the right)
Raster images are just grids of pixels, like what comes out of a digital camera or a scanner. The file doesn't know what those pixels mean. Web images and digital paintings are most often raster.
- Adobe Photoshop, GIMP, Krita, Corel Photopaint and Pixelmator are primarily raster (some have a few very basic vector tools too, but the images they create are raster).
- Most digital painting programs and apps like ArtRage, Sketchbook, Layerpaint and Procreate are raster.
- JPG, GIF, PNG, TIFF, BMP are all common raster image formats. PSDs (Photoshop files) are raster too (but can sort-of contain sort-of vector shapes). PDFs can contain both.
Vector images are made of separate shapes, lines, paths etc. They're more flexible as each shape is separate and you can scale up and down as much as you like, but it's harder to make the images look natural.
- Adobe Illustrator, Inkscape, Sketch, Affinity Designer and Corel Draw are primarily vector (although some have a few tools that add raster effects).
- Most CAD and 3D rendering programs like AutoCAD, Maya, Blender and Cinema4D work with (more complex) vectors.
- EPS, SVG and AI (Illustrator) are the most common vector formats. They can all contain embedded raster images. PDFs can contain both - it's good practice to produce PDFs where everything that can be vector is, and only things like photos are raster.
In general, if you can use vector, it's a good idea to. It'll be more flexible for scaling, easier to edit, and you won't have to worry about the resolution being high enough for print (vector images have infinite resolution).
It's common to work with a mix of the two e.g. where you have a photo and other elements.