3. Vectors

Sometimes it is very useful to be able to change the size of an image without losing quality.

This font for example can be made in many different sizes.


 small        bigger      Bigger still


Notice that the shape of each letter is still smooth no matter what the size.  You can make it as large as you like and it will not pixellate or go fuzzy as a bitmap image would.  This is an example of a VECTOR IMAGE. 

Instead of storing every single dot in the picture as a bitmap, vector images store a set of instructions of HOW to draw the shape.  For example, consider the line below - this is a vector graphic:


      a ____________ b


The instructions would be something like this:

  1. Draw a dot at point "a"
  2. Draw a dot at point "b"
  3. Connect the points together with a straight line of a certain thickness
  4. Colour the line red

The size of the file does not change if the image needs to be larger - the same instructions will make the image as large as you like, and yet the line would always remain smooth and clear.

Some images are not suitable for storing as a vector image. For example, a detailed photograph would need so many vector instructions to recreate it, that it is better to store it as a BITMAP.

On the other hand simple geometric shapes such as letters, autoshapes and logos are ideal for storing as vector images.


Vector graphics are vital where scaling and dimension is important. For instance Computer Aided Design (CAD) files are created in vector format. Each vector within the drawing has an exact dimension relative to the origin and scaling factor. This allows engineers to precisely define the object being designed. Although the simplest vector is a straight line going from A to B, curves can also be defined mathematically so very complex shapes can be represented.

Animation packages also make use of vectors, for instance Flash support vector images.


Another useful property of vector images is that they can be grouped into objects which is why sometimes vector graphics are sometimes called 'object orientated graphics'. For example, you could design a car door in a CAD package. Then another engineer takes that CAD design and adds it to his car body design, he can easily duplicate it for four doors and so on.

Individual vector objects can be edited independently, they can also be duplicated and re-sized with only a small increase in file size.

Exam questions

In an exam question, if you are asked to describe a vector graphic, here is a summary of the points made above:

Vector graphics are created by mathematical equations and calculations
Points in a vector graphic are described by a relative distance from the origin
Vector graphics can be resized, made larger or smaller without losing any clarity
Every line in a vector graphic is described by its features i.e. length, thickness, colour of line etc
Objects in a vector graphic can be grouped together e.g. clipart
the individual elements that make up the vector graphic can be edited independently, for example, moving, resizing, rotating, recolouring


challenge see if you can find out one extra fact on this topic that we haven't already told you

Click on this link: Vector Graphics