Year 9 Digital Media and Sound Assessment

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

There is a term for the number of individual elements in an image. What is it?

• revolution

• resolution

• bit depth

• pixels

What is the bit depth of this image?

• 7 colours

• 8 colours

• 3 bits

• 24 bits

If an image uses 'RGB colour', then how many bits are used to represent the colour of each pixel?

• 3

• 8

• 24

• Over 16 million

Answer explanation

Twenty four bits - 8 bits for red, 8 bits for green, 8 bits for blue.

How many bits make a byte?

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

• it consists of 600 pixels and 400 colours

• it consists of 240,000 pixels

• It requires 5,760,000‬ bits to be represented

• It requires 2,400,000 bytes to be represented

Answer explanation

it is 600 pixels wide X 400 pixels high, so that makes 240,000 pixels in total.

If it has a bit depth of 10 bits, it might also take up 2,400,000 bits.

If it has a bit depth of 24 bits (RGB), it might also take up 5,760,000‬ bits.

You check the file "Properties" (or "Get Info") of an image and see that its size is 800kB (kilobytes). Select an equivalent size from the list below:

• 800kb (kilobits)

• 800,000 bytes

• 100kb (kilobits)

• 800,000,000 bytes

• 800 billion bytes

You calculate the representation size that an image is supposed to have - 24MB. You find that the actual size is much smaller than you expected ~ 3.2MB. What one word explains this?

• compression
• countering

• bit depth

• metadata

This image of a flower has a resolution of 2,000⨉2,000 and its colour depth is 10 bits. What is the resolution of the image in megapixels?

• 4

• 4,000

• 4,000,000

• 40,000,000

Answer explanation

pixels = 2000 * 2000

pixels = 4,000,000

kilopixels = 4,000,000/1000

megapixels = 4,000/1000

megapixels = 4

Remember:

1 kilopixel = 1,000 pixels

1 megapixel = 1,000,000 pixels

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

• The camera can capture images with a file size of 8 megabytes.

• The camera can capture images with a resolution of 8 thousand pixels.

• The camera can capture images with a resolution of 8 million pixels.
• The camera can capture images with a bit depth of 8,000,000.

Select the definition that you find most appropriate for the colour depth of an image:

• How many different colours there are in the image

• How ‘sharp’ the image is

• How many pixels the image consists of

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