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New
New
Year 10
AQA

Representing bitmap images

I can describe how computers represent bitmap images.

icon-background-square
New
New
Year 10
AQA

Representing bitmap images

I can describe how computers represent bitmap images.

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Lesson details

Key learning points

  1. A pixel is the smallest element in an image.
  2. A bitmap image is one that is represented by a grid of pixels.
  3. The colour a pixel should display is described by a binary sequence.
  4. The colour depth of a bitmap image quantifies the number of bits used to represent each pixel.
  5. The resolution of an image describes the total pixels an image contains based on its width and height.

Keywords

  • Pixel - the smallest element of an image

  • Colour depth - the number of bits used to represent the colour of each pixel

  • Resolution - total amount of pixels an image contains based on its width and height expressed in pixels

Common misconception

Bitmap images that are large on screen are always poor quality.

The quality of a bitmap image depends on its resolution, not just its size on the screen. A high-resolution bitmap can appear sharp and detailed, while a low-resolution bitmap may look pixelated when enlarged.


To help you plan your year 10 computer science lesson on: Representing bitmap images, download all teaching resources for free and adapt to suit your pupils' needs...

A bitmap image can be used to demonstrate changes caused by adapting its physical size. Pupils like to see images they are familiar with get stretched so they can begin to see the individual pixels that make up the image.
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Lesson video

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6 Questions

Q1.
What is a binary digit (bit)?
A group of 8 bits
A method of character representation
Correct answer: The basic unit of data within a computer system that has the value 0 or 1
A sequence of symbols
Q2.
What is a group of 8 bits called?
Correct Answer: byte, a byte
Q3.
What does a character set do?
Correct answer: Matches characters to a unique binary sequence
Represents images in bitmap format
Uses up to 32 bits per character
Measures file size
Q4.
Which character representation method uses 8 bits per character?
Correct Answer: ASCII
Q5.
What is the method of character representation that uses up to 32 bits per character?
Correct Answer: Unicode
Q6.
How many possible states are there in a sequence of 3 bits?
4
6
Correct answer: 8
16

6 Questions

Q1.
Which term refers to an image format that is composed of a grid of individual pixels, each with its own colour value?
Resolution
Colour Depth
Correct answer: Bitmap
Pixel
Q2.
What determines the quality of a bitmap image?
Its size on the screen
Correct answer: Its resolution
The number of colours it uses
The type of computer used
Q3.
What is the smallest element of a bitmap image?
Correct Answer: pixel, a pixel
Q4.
Why might a bitmap image look pixelated?
Correct answer: Low resolution
High colour depth
Large file size
Small screen size
Q5.
Which term describes the number of bits used to represent the colour of each pixel in an image?
Resolution
Pixel
Bitmap
Correct answer: Colour depth
Q6.
Match the term to its definition:
Correct Answer:8-bit colour depth,Allows for 256 different colours.
tick

Allows for 256 different colours.

Correct Answer:16-bit colour depth,Allows for 65,536 different colours.
tick

Allows for 65,536 different colours.

Correct Answer:24-bit colour depth,Allows for 16.7 million different colours.
tick

Allows for 16.7 million different colours.