Image Representation Lesson 2

What does colour depth mean?

• The number of colours in a digital image

• The number of bits used for each pixel in a digital image

• The number of pixels in a digital image

• How vibrant a colour is in a digital image

How many colours can you have with a colour depth of 1?

• 1 colour

• 2 colours - black & white

• 4 colours

• 32 colours

How many colours can you have with a colour depth of 2?

• 1 colour

• 2 colours - black & white

• 4 colours

• 32 colours

If you have 3 bits for each pixel, what are the 3 colours that each pixel is made up from?

• red, green, blue

• red, yellow, blue

• black, white, red

• cyan, magenta, yellow

How many colours can you have with 3 bits per pixel?

• 3

• $2^3$ = 8

• 2 x 3 = 6

• 3 x 3 = 9

In general, how many colours can you have with a colour depth of n (i.e. n bits per pixel)

• $2^n$

• $n^2$

• 2 x n

• n

What is metadata?

• Extra data that is added to an image which tells the computer how to display it.

• Part of the image that helps to reduce the file size

• A technique used to hide secret messages in an image

• None of these

What essential metadata is included with a bitmap image?

• Resolution and Colour Depth

• Location and Colour Depth

• Resolution and Location

• Location and Camera Type

Why does the computer need the Resolution in the metadata? (2 reasons)

• To know when to move to the next row when creating an image from the binary values

• To know how to display the colours for the image

• To know how many pixels to read from the binary file in total

• To allow the image to be printed

Why does the computer need the Colour Depth in the metadata?

• To know how many bits to read from the binary file for each pixel in the image

• To know when to move on to the next row when displaying the image

• To know where the light and dark patches are to adjust the colour balance

• To allow you to zoom in and out of the file in an image editor