Humm..such a theoritical definition isn't it. It's easier to see image below.
Example showing effect of vector graphics versus raster graphics. The original vector-based illustration is at the left. The upper-right image illustrates magnification of 90x as a vector image. The lower-right image illustrates the same magnification as a bitmap image. Raster images are based on pixels and thus scale with loss of clarity, while vector-based images can be scaled indefinitely without degrading quality.
Do you have a bitmap image? You want to resize, rescale it? Of course, bitmap/raster graphic quality will degrade. So you need to vectorize it. Check this example below.
Image above is taken from photograph. Custom vector service can change into another character. Look at the right image. It's look different with the left photograph. It's looks nice.
Or do you want to vectorize your own photograph?
Check this detailed Lady Gaga vector graphics.
Have no skill to do that? You can ask Ndopart.com , provide bitmap to vector service. Just contact him at his blog here