Text, Sound & Images

Character Sets

What is a character set?

• All characters and symbols that the computer recognises/uses
• A list of characters recognised by the computer hardware and software
• Each character and symbol has a unique value

Unicode vs ASCII

• UNICODE has greater range of characters than ASCII
• UNICODE represents most written languages in the world while ASCII does not --- ASCII used for English only
• UNICODE can represent emojis, ASCII does not
• ASCII uses 7 or 8 bits per character whereas UNICODE uses 16/32 bits per character
• UNICODE has 60/4 billion characters, ASCII has 128/256 characters

Advantage of using Unicode instead of ASCII

• It can representmore characters
• It can represent emojis/symbols
• It can represent more languages

Disadvantage of using Unicode instead of ASCII

• Each character requires morestoragespace

Describe how text is converted to binary

• A character set is used such as ASCII/UNICODE
• Each character has a unique binary value

Explain how the word \"RED\" is represented using a character set

• Unique binary/denary number given for each character
• The code for R is stored, then the code for E then D in sequence

Sound

Sound Definitions

• Sample rate:the number of samples taken per second
• Sample resolution:the number of bits per sample
• Pixel:One square/circle of onecolour // the smallest component of the image

How does a computer represent sound?

• A sound wave is sampled for sound to be converted to binary, which is processed by a computer

How does a computer represent sound?

• Recorded using a microphone
• Sound wave is sampled... measuring the height/amplitude
• Each amplitude has a unique binary value
• The sample rate is set that is the number of samples taken per second
• The sample resolution is set that is the number of bits used for each sample
• Each sample taken is converted to binary

What happens if the sample rate/sample resolution is increased?

• The file size will increase
• The accuracy of the recording will increase
• Larger dynamic range
• Will take a longer time to download/upload

Images

Image Definitions

• Resolution:the number of pixels in an image
• Colour depth:the number of bits used to represent each colour
• Pixel:smallest component of the image

How does a computer represent images?

• An image is a series of pixels that are converted to binary which can be processed by a computer

What happens if the colour depth/resolution is increased?

• The file size will increase
• The quality of the image will be increased
• Will take a longer time to download/upload