Y8 - Image Binary - SCITT 2026

• Computing
• Lower Secondary (Key Stage 3)

Y8 - Image Binary

How images are represented on

your devices

How do you think a computer stores an image?

Key objectives

1) Vector vs Bitmap - what is the difference?

2) Bitmaps and colours - how are they drawn?

3) Bit depth - how are colours represented?

4) Hex - how do we simplify our colours?

5) Resolution - how many pixels allowed for your image? 

6) Compression - which keeps the best quality for your content?

Vector Use

Bitmap use

Which of these posters do you like, and why?

What information did you take from them?

VECTOR

BITMAP

Uses calculations

smaller in file size

larger in file size

will pixelate

uses pixels

Used for real photos

Will not pixelate

Used for maps

Bit depth

How many bits allocated per pixel

How many colours can be used in 2 to the power of 3?

1. 6
2. 8
3. 10
4. 12

Create a BITMAP

Click here to open

Challenge link

Only use this slide for further explanation eg an extended we do or computer issues.

RGB 24 bit colour

24 bits per pixel

8 for red

8 for green

8 for blue

16.7 million options

one pixel of pure green would be 000000001111111100000000

How many colours could you represent using a bit depth of 24

1. 24,777
2. 24,777,224
3. 16,726
4. 16,777,216

Hex makes it easier

6 digits of hex

instead of 24 binary digits

Easier to remember

Easy to convert to binary

• 000000 = black
• FFFFFF = white
• 960080 = lilac

Try this

Put this number into google

#642240

What do you think it is?

answer for next slide:

0110 0100 0010 0010 0100 0000

Recall: what is "#642240" in binary?

0110 0100 0010 0010 0100 0000 - the school purple/burgundy colour!

Image resolution

Number of pixels across the height and width of the image

Density of pixels in a given area (usually dots per inch)

Other sizes

Challenge

Research the term "metadata" when linked to storing images

get some examples

Sentence starters:

One example is ...

Second example is ...

One risk is ..

Share 2 examples of metadata
and 1 risk

Extension:

Learning about compression

Click me

Watch this video

What is the difference between lossy and lossless compression?

Which topic was the most difficult for you today?

Vector vs bitmap?

Bitmap and basic colours

Bit depth and colour representation

Hex simplification

Screen resolution

Compression