Images

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 Vector Image Bitmap 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 Bits 4 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