1. Images Data Representation

2. Objectives  Understand the terms bitmap & pixel  Understand how bitmap images are stored using binary in a computer system  Understand the term metadata and what it is for (height, width, colour-depth)

3. Types of images  There are two ways in which we can store an image on a computer Bitmap Image Vector Image

4. Looking at Bitmaps in detail  Bitmap images are a collection of pixels arranged in a grid pattern  A pixel is a point on the screen which is made up of 3 different colours – RGB (Red, Green & Blue).  These colours can then make any colour we wish, by mixing them together.

5. How to represent colour in binary  Just like other data colour is represented in binary  Colour groups or a collection of colour is called a pallet  We can change the number of colours in a pallet by changing the number of bits that we use of colour. 1 bit 2 Bits4 Bits 2 Possible values 0 = Black 1 = White 4 Possible values 00 = Black 01 = Dark Grey 10 = Light Grey 11 = White 16 Possible values 0000 = Red 0001 = Orange …… 1110 = Indigo 1111 = Violet

6. Parts of the image  An image will come with two parts  Metadata  Image data Meta Data It specifies the picture’s resolution, i.e 14 px by 14px The colour depth (how many pixels are used for the pallet) Image Data This is the binary that makes up the image Basically a long string of 0s and 1s

7. Time to play It’s now time to have a go at making your own bitmap image using Hama beads