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Any image in a vectorial format consists of great number of components which can be edited
independently from one another. These parts are named objects. Therefore, sometimes vector
graphics is named object-oriented. To combine several objects, it is possible to create a new object,
that is why objects can have a complicated appearance. For every object, its sizes, curvature and
location are stored as numerical coefficients. Due to this there is a possibility to scale an image with
the help of simple calculations, simple multiplying of graphic elements. Thus quality of image
remains without changes. For example, when scaling a segment coordinates of supporting points are
transferred, but sizes of points which fill an interval between these key points of a segment remains
unchangeable. Only number of these points are changed. Therefore, unlike the increasing segment
of bit-mapped graphics a vectorial segment remains clear and of high-quality. Figure 9.4 shows the
increasing segment made with the help of bigmap on the left figure 9.4, shows this segment made
with the help of vector graphics on the right figure 9.4. Using vector graphics, it is possible not to
think what we do: prepare a miniature emblem or draw two-meter transparency. We work with a
picture quite identically in both cases. At any moment we can scale an image to any sizes without
the loss of quality. The vectorial programs are irreplaceable in those areas of graphic arts, where the
maintenance of high-quality and clear contours - in design, technical drawing, drawing-graphic and
designer works is very important.

a b
Figure 9.4 – Increasing segments made with the help of bigmap graphics (a) and vector graphics (b)

No less important advantage of vectorial method of coding images is that the graphic files of
vector graphics have a considerably smaller size, than the files of bit-mapped graphics. It is related
to the fact that not an image is stored but some important data, in particular coordinates of
supporting and managing points, using which the program reproduces an image for the first time. In
addition, a description of colors increases a file size slightly, as given data about color identical to
the whole object.
But on the other hand, vector graphics has some drawbacks to be mentioned.
The substantial drawback is programmatic dependence, as there is no principle possibility to
create the unique standard format which would allow to open freely any vectorial document in any
vectorial program.
As in a bit-mapped graphics a basic display element is a point, so in vector graphics a basic
display element is a line which is named a vector, and it got its name from it – vector graphics.
Clearly, there are lines in a bit-mapped graphics, but there they are considered as
combinations of points. For every point of line in a bit-mapped graphics one or some barns of
memory are taken (the more colors can have points, the more barns are selected for them.
Accordingly, the longer raster line, the more memory it occupies. In vector graphics the amount of
memory, which needs to be selected a line does not depend on the sizes of a line, as a line appears
in the form of formulas and to be more exact in the form of several parameters.

QUESTIONS FOR SELFCHECK

1. What are basic tasks of computer graphics?
2. Where are computer graphics using?
3. What types of computer graphics do you know?
4. Describe bit-mapped graphics.
5. Describe vector graphics.

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