Raster to Vector – What You Need to Know
Raster and vector are terms that you may have heard before, but may not know exactly what they mean. These two terms are important to anyone who works with graphic images, whether your images are of the artistic variety (like logos and other graphics or commercial advertising images), or architectural and manufacturing designs.
What are Raster Graphics?
Raster graphics are made of pixels. Pixels are tiny little grid squares that are filled with color. These little grid squares are packed tightly together to create an image. Sometimes raster graphics can become pixelated when they are enlarged, that is you can begin to see the blank spaces between the little squares of color, and the image begins to visually ‘fall apart.
Because of this, raster graphics are resolution dependent. The higher the number of pixels per inch (PPI), the higher the resolution of the image, and the greater the enlargement potential of the image. PPI describes the screen resolution of your computer, whereas DPI or dots per inch is used to describe print resolution, or how closely your printer deposits the little dots of ink or the printed page in order to show the printed image. In either case, an image looks “pixelated” when the image is below the required PPI or DPI for optimal resolution.
What are Vector Graphics?
Vector graphics are composed of mathematically drawn lines, points, and fills. Because of this, a vector image can be scaled up or down, and I mean, way up and way down, without losing resolution like a raster image will. You can take a vector image and size it to an 8 ½ by 11-inch paper or smaller as well as you can size it to a huge sign that is 70 by 91 feet or more and it will still be true to the image that you’ve designed. For this reason, a vector image is not resolution dependent.
CAD Design vs. Artistic Design
Because of the versatility of vector files, most CAD design is done in vector-based CAD programs, such as AutoCAD. Artists often find a combination of both raster and vector images used in their design activities, because vector can be slightly limiting when it comes to the level of detail.
Since vector images are composed of objects, not pixels, artists can change the color of individual objects without worrying about individual pixels. Coloring vector objects are similar to coloring with crayons in a coloring book. A drawing program will enable a user to click inside an object and define its color. A drawing program will also enable a user to define the color and width of lines. Coloring vector images are much easier than coloring raster images. The same is true for CAD designers.
Because vector images do not need to keep track of each individual pixel in an image, only mathematical descriptions, vector files are generally much smaller in size than comparable raster files. However, sometimes it is necessary to combine raster and vector files. That is where a hybrid program that enables users to work with both types of files can be useful. In the CAD arena, on such hybrid program is WiseImage.
Types of Vector Programs
Artistic vector graphic art is most commonly done in programs such as Illustrator, Freehand, Corel Draw, Flash, Inkscape, Fireworks, or other “vector” illustration programs. Vectors in these programs (at the hands of skilled artists and draftsmen) can achieve a nearly photo-like quality or be beautifully abstract. Other vector formats include EPS (Encapsulated PostScript), WMF (Windows Metafile), AI (Adobe Illustrator), CDR (CorelDraw), DXF (AutoCAD), SVG (Scalable Vector Graphics) and PLT (Hewlett Packard Graphics Language Plot File).
AutoCAD is most commonly used for CAD design…that is architectural, engineering and construction related design as well as product design for manufacturing.