Computer Revision6 [Text, Sound & Images]

• Text is converted to a unique binary number using the computer's character set to be processed by the computer

1. The symbols that the computer uses

2. A list of characters recognised by the computer hardware and software

1. ASCII (American Standard Code for Information Interchange)

2. Unicode

1. Uses 7/8 bits

2. Only 128 (2⁷) or 256 (2⁸) characters can be represented

3. Many characters in other group languages cannot be represented

1. Uses 16, 24 or 32 bits

2. It is designed so that most characters in other languages can be represented

3. It allows for a greater range of characters and symbols including languages and emojis

1. ASCII uses 7 or 8 bits per character whereas Unicode uses up to 32 bits per character (Unicode requires more bits per character than ASCII)

2. Unicode has a greater range of characters than ASCII

3. Unicode represent most written languages in the world while ASCII is used for English only

1. The amplitude of the sound wave is determined at set time intervals to get an approximation of the sound wave

2. Each sample is stored as a binary number

3. Samples are stored in order in a file

• It refers to a value at a point in time

• It is the number of samples taken per second

1. A sound wave is sampled to be converted to binary which is processed by a computer

2. Each sample is stored as a binary number

3. Samples are stored in order in a file

1. Increasing the sampling rate means more samples per second and hence more bits per sample and file size will be larger

2. Increasing the sampling rate will increase the accuracy of the digitised sound

1. Decreasing the sampling rate means fewer samples per second and hence fewer bits per sample and file size will be smaller

2. Decreasing the sampling rate will decrease the accuracy of the digitised sound

• It is the number of bits used to store each sample

1. Increasing the sampling resolution means larger file size

2. Increasing the sampling resolution gives more accurate representation of the sound

1. Decreasing the sampling resolution means smaller file size

2. Decreasing the sampling resolution gives less accurate representation of the sound

1. Bitmap

2. Vector

1. Picture element

2. Smallest addressable area on screen / image

1. Has fewer pixels

2. Poor image quality

3. Takes less memory space

1. Has many pixels

2. Good image quality

3. Takes more memory space

1. An image is a series of pixels

2. The colour of each pixel is represented by a unique binary pattern

3. The colour of each pixel is stored

1. An image is a series of pixels

2. The colour of each pixel is represented by a unique binary pattern processed by a computer

3. The colour of each pixel is stored

• It is the number of pixels in an image / screen

• The number of bits used to represent each colour

1. Increases file size

2. Increases quality of an image

1. Decreases file size

2. Decreases quality of an image

1. Increases file size

2. Increases quality of an image

1. Decreases file size

2. Decreases quality of an image

• File size = Number of pixels * colour depth