1.2 Text,Sound Images
How computers represent text sounds and 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 and emojis while ASCII does not ASCII used for English only
- ASCII uses 7 or 8 bits or one byte whereas UNICODE uses up to 4 bytes per character
- UNICODE is standardised while ASCII is not
How does a computer represent text?
- A character set is used
- ..such as ASCII/UNICODE
- Each character has a unique binary value
Sound
Sound Definitions
- Sample rate: the number of samples taken per second
- Sample resolution: is the number of bits per sample
How does a computer represent sound?
- A sound wave is sampled for sound to be converted to binary, which is processed by a computer
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: is 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