Vector graphics is a technique used in computer graphics to describe an image. An image described with vector graphics is called a vector image.

In vector graphics, an image is described by a set of geometric primitives that define points, lines, curves and polygons to which colors and even shades can be assigned. It is radically different from raster graphics in that in raster graphics images are described as a grid of appropriately colored pixels.

The main advantages of vector graphics over raster graphics are as follows:

  • Ability to express data in a form directly understandable to a human being (e.g., the SVG standard);
  • ability to express data in a format that takes up (much) less space than the raster equivalent;
  • ability to enlarge the image arbitrarily, without loss of image resolution.

The first point translates into the possibility for a person to intervene directly on the image even without making use of graphics programs or even without extensive knowledge about it. For example, to translate text in an SVG image, it is often sufficient to open the file with a text editor and edit the strings read into the file.

Such a system of describing graphical information also has the undoubted advantage of greater data compression: in practice, a vector image will take up much less space than a corresponding raster image, with a reduction in RAM and mass storage occupancy, mainly in geometric shapes or spot color fills. It is, moreover, easier to manage and edit, as there is less data involved in each individual update operation. This makes vector particularly suitable for handling large amounts of data such as cartographic data that are typically handled in vector mode; finally, enlarging or reducing the size and proportions of the subject produced in vector does not significantly affect the weight of the image itself; filling shapes with spot colors is generated by simple mathematical functions and is, therefore, extremely light in terms of memory used.

Vector Graphics vs. Raster Graphics

Vector graphics, being defined through mathematical equations, are independent of resolution, whereas raster graphics, if enlarged or displayed on a device with a higher resolution than the monitor, lose definition. A line running across the screen transversely if it is represented using raster graphics is stored as a sequence of colored pixels arranged to form the line. If you tried to enlarge a section of the line you would see the individual pixels that make up the line. If the same line were stored vectorially, the line would be stored as an equation starting at a point identified with initial coordinates and ending at another point defined with final coordinates. Enlarging a section of the line would not produce visual artifacts or the display of individual component pixels in the image, since the line would always be displayed at the maximum resolution allowed by the monitor.

For example, taking a 2×24-pixel large vector image and increasing the resolution to 1024×768 will result in an image that has the same definition as when it was 2×24. If we zoom in on a bitmap type file adapted to 800×600 px and enlarge it to 1024×768 px the definition is lower, this is because the processor does not recalculate the definition of the image as it does in vector images but uses the same information (pixels) of the image on a larger area.

How to make the best use of vector graphics

The use of vector graphics is recommended when logos, drawings and graphic shapes need to be represented. Elements that applied to even large products-such as floor displays, counter displays, cardboard displays, in panels used forwindow display -will not lose their maximum display quality.
In general, however, the use of vector graphic elents is always preferable when we need to use drawings and shapes in our graphic layout and not photo realistic images. For example, the brand logo to be applied to some custom packaging solutions-which can be boxes, as well as cases, custom shoppers, cardboard tubes, hat boxes, clutch bags, envelopes, window signs, plaques, plexiglass giftware, and furniture accessories-it is highly advisable to include it in vector format.