Data Representation Year 9 Assessment

Q1.  This image consists of individual elements. What are they called?

An image with a 600⨉400 resolution and RGB colour

Q1.  If this image uses ‘RGB colour’, then how many bits are used to represent the colour of each pixel?

• 3

• 8

• 24

• 16 million

The resolution of this image is 600⨉400. This means that:

• A.     It consists of 600 pixels and has 400 colours.

  .

• B.     It consists of 240,000 pixels.

• C.      It requires 240,000 bits to be represented.

• D.     It requires 240,000 bytes to be represented.

Q1.  You check the file properties of the image and see that its size is 800kB (kilobytes). Select one or more equivalent sizes from the list below:

• A.     800 thousand bytes

• B.     800 million bytes

• C.      800 billion bytes

• D.     100kb (kilobits)

• E.      6400kb (kilobits)

Q1.  You calculate the representation size that this image is supposed to have. You find that the actual size of 800kB is much smaller than you expected.

Use one single word to explain this.

This image of a flower has a resolution of 2,000⨉2,000 and its colour depth is 16 bits (this is a compact version of RGB where 5 bits are used for red and blue and 6 bits are used for green).

What is the resolution of the image in megapixels?

• 2000 ⨉ 2000 = 4 million pixels = 4 megapixels

• 200 ⨉ 200 = 4 million pixels = 4 megapixels

Q1.  This image of a flower has a resolution of 2,000⨉2,000 and its colour depth is 16 bits (this is a compact version of RGB where 5 bits are used for red and blue and 6 bits are used for green).

How many binary digits are required to represent the image?

• 4 megapixels  ⨉ 16 bits per pixel = 64 megabits (64 million bits)

• 4 megapixels  ⨉ 16 bits per pixel = 64

Convert that 64 MB into bytes (or kilobytes, megabytes, gigabytes, or whatever you find most appropriate):

• To convert bits to bytes is to divide in groups of 2.

  64 megabits ÷ 2 = 32 megabytes (32 million bytes)

• To convert bits to bytes is to divide in groups of 8.

  64 megabits ÷ 8 = 8 megabytes (8 million bytes)

Q1.  The technical specifications of your new phone report that it has an 8-megapixel camera. What does that mean?

• A.     It takes pictures that consist of 8 big pixels.

• B.     It takes pictures that consist of 8 thousand pixels.

• C.      It takes pictures that consist of 8 million pixels.

• D.     It takes pictures that are 8 megabytes in size.

Q1.  Select the definition that you find most appropriate for the resolution of an image:

• A.     How ‘sharp’ the image is

• B.     How many pixels the image consists of ✔

• C.      How many different colours there are in the image

• D.     How many binary digits are used to represent the colour of each pixel

• E.      How many binary digits are used to represent the image