images data representation. objectives understand the terms bitmap & pixel understand how...
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ImagesData Representation
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)
Types of images
There are two ways in which we can store an image on a computer
Bitmap Image
Vector Image
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.
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 bit2 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
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
Time to play
It’s now time to have a go at making your own bitmap image using Hama beads