Line art is a monochrome digital image that does not use dithering or halftone. I like to think of it as an electronic coloring book. When scanning line art, 600 dpi is generally good enough unless you have a tiny original. Once you have touched up your scan in GIMP, Photoshop, or the like, you can use other tools to trace it into an SVG or EPS file that can be scaled to any size; however, tweaking autotrace settings is not an exact science, so practice with your children's coloring books.