I believe you are thinking of vector images. Raster refers to there being individual pixels to create an image (which gets "jaggy" when it is enlarged). Vector images use math (ohhh, scary) to define curves, so they don't change as they are redrawn. The math just makes everything proportionally larger as it is scaled.
-phil
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Muller's Theorems No. 5:Corollary 1 - Any totally successful project was not sufficiently daring.