Images, Sound and Compression

True or False? Compression reduces the size of a file to make it smaller

• True

• False

Lossy or lossless? This type of compression does not get rid of any data

• Lossy

• Lossless

• Both

Lossy or lossless? This type of compression gets rid of some information

• Lossy

• Lossless

• Both

Lossy or lossless? All information and quality is kept

• Lossy

• Lossless

• Both

Lossy or lossless? Some quality is lost

• Lossy

• Lossless

• Both

What is compression?

• To convert one file to another
• To reduce the size of data to save space
• To minimize the time taken for a file to be downloaded
• To compress something by pressing it very hard

What is the smallest representable part of an image?

• Pixel

• Bit depth

• Sample

• Resolution

How is the resolution of an image calculated?

• Width in pixels * height in pixels

• Colour depth * number of pixels

• Number of pixels squared

• Sample rate * sample resolution * length in seconds

Colour depth defines...

• How many bits are needed to store each pixel

• How many pixels are in an image

• The file size of a bitmap image

• The sample rate of sound

A bitmap image of 20 by 20 pixels using a colour dept of 8 bits would have a file size of around:

• 400 bytes

• 3200 bytes

• 40 bytes

• 320 bytes