Computer Science : S1 : L9 : Representing Images

Bitmap Images are made of pixels . A pixel is a tiny dot of only one colour , when combined with many more it creates an image. Vector images are created from shapes(Not only Squares) These images can be made bigger or smaller without losing quality.


Bitmages : 

  • Smaller File Size

  • Changes as enlarges

Vectors : 

  • Large file size

  • Does Not change when enlarged.


The more bit per pixel = More colours combinations + More data that the picture takes with it 


In Bitmap each pixel is given a binary value. If a bitmap was made using one bit per pixel it would only allow 2 values (1,0). Increasing The bits per pixel increases the available colour combinations. It is easier to understand with more colours 


Image resolution - The number of pixels in a image

Colour Depth - The number of bits that are used to represent each colour (8 bit = 256)

MetaData - Data about Data

Calculator Image size : 

  1. Find The total number of pixels 

  2. Times the new number by the colour depth 

  3. Then divide by 8 to change from bit to byte


  • A bitmap graphic is made up of pixels

  • Each pixel is represented in binary

  • The resolution determines the number of available colours for a image 

  • The greater the resolution/Colour depth of the image the greater the file size