What's the difference between vector graphics and raster graphics?

Also, when would you use one vs the other?

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"When would you use vs the other" is a bit broad I think. A bit more context would be needed (because in digital media, you'll often have to use raster images even if vector would be the "right thing") –  Pekka 웃 Jan 6 '11 at 18:00
I'm just looking for typical examples in an ideal world. I understand that often you have to use raster images, but I'm just looking for the generic use cases. –  PearsonArtPhoto Jan 6 '11 at 18:56

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.

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to add to Pears answer: Vector images are good for Logos, and Icons, when the size is indeterminate. Raster images are good for backgrounds and photos, when you know how big you want something to be. –  zzzzBov Jan 6 '11 at 21:42

@Pearsonartphoto already puts it nicely. In an effort to find the shortest possible definition that is still correct:

• Vector graphics are a collection of geometrical elements (primitives like circles, squares, triangles... as well as polygons and curves) that you can enlarge to any size.

• Raster (Pixel) graphics is a collection of coloured dots. You can't enlarge it without the dots starting to show.

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Resizing the raster graphic down doesn't degrade the image as much as enlarging, though. –  koiyu Jan 6 '11 at 18:26
@koiyu cheers, I meant "enlarge". Fixed –  Pekka 웃 Jan 6 '11 at 18:26
@koiyu It doesn't at all, if you use Super Sampling. –  muntoo Jan 7 '11 at 5:05

NOTES: Inkscape would be an example of a Vector Graphics editor, while GIMP/Photoshop/Paint.NET/etc are suited to editing raster images.

Ever notice that as you zoom into an image, the quality gets lower? That's a raster image. A raster image is like the one your digital camera takes. They are usually in the formats JPG (lossy), GIF (lossless), PNG (my favorite; lossless), and many others.

This is a Raster Graphics editor in action:

Meanwhile, vector images are in the format of SVG, and some others. Their applications are not usually for everyday use. (Ordinary people don't use vector graphics.) You can't upload .svg files, normally, and not everyone has an editor (even though Inkscape is free).

They're based on the mathematical idea of vectors:

Vector graphics can do more than just lines, though. They can draw other "primitives" like squares, circles, curves.

Here's an image that explains the difference best: http://en.wikipedia.org/wiki/File:VectorBitmapExample.svg

Notice I couldn't upload because it was in .svg (vector) format. You CAN convert it to a raster, though, but I was too lazy.

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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, just what colour they are. Web images and digital paintings are usually raster too (but not always). Adobe Photoshop, GIMP, Krita, Corel Photopaint and Pixelmator are primarily raster (they have a few very basic vector tools too, but the images they create are raster).

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 and Corel Draw are primarily vector (although some have a few tools that add raster effects).

In general, if you can use vector, it's a good idea to. It'll be more flexible for scaling 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.

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protected by Matt♦May 22 at 15:17

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