Data Reprensentation Flashcards
Why is hexadecimal used in computer science?
Hexadecimal is used to make binary numbers easier to read for humans, avoid mistakes and allow us to quickly convert into binary.
What are the advantages of Unicode compared to 7 bit ASCII?
Wider Character Support: Covers characters from most languages, symbols, and emojis.
Multilingual: Enables use of multiple languages in one system.
Flexible Encoding: Supports UTF-8, UTF-16, and UTF-32 for diverse needs.
Compatibility: Backward compatible with ASCII.
Global Standard: Ensures consistency across platforms.
Complex Script Support: Handles diacritical marks and bidirectional text.
Non-Alphabetic Symbols: Includes math symbols, technical icons, and more.
What is colour depth?
Colour depth is the number of bits used to represent each pixel.
Describe using examples how the number of pixels and colour depth can affect the file size of a bitmap image.
Pixels Count: More pixels (higher resolution) means more data to store. Example: A 1920x1080 image has 2,073,600 pixels, while a 640x480 image has only 307,200 pixels.
Colour Depth: Higher colour depth requires more bits per pixel. Example: A 24-bit image (16.7 million colors) uses 3 bytes per pixel, while an 8-bit image (256 colors) uses 1 byte per pixel.
Combined Effect: Higher resolution and greater colour depth increase file size significantly. Example: A 1920x1080 image at 24-bit depth is larger than the same resolution at 8-bit depth.
what is the formula for calculating bitmap image sizes?
Size = (bytes) = (W x H x D)/8
what is a sample
a sample is a measure of amplitude at a point in time.
what is sample rate?
Sampling rate is the number of samples taken in a second and is usually measured in hertz (1 hertz = 1 sample per second).
what is sample resolution
Sample resolution is the number of bits per sample.
what is the formula for calculating file sizes of sound?
File size (bits) = rate x res x secs
How is sound stored on a computer?
sound is analogue and that it must be converted to a digital form for storage and processing in a computer.
Explain what data compression is.
the process of reducing the size of a file or dataset by encoding its content in a more efficient way. This allows the same information to be stored or transmitted using fewer bits
Why does data need to be compressed
Save storage space and reduce transmission time over networks.
Explain how data can be compressed using run length encoding (RLE).
By replacing consecutive identical values (runs) with a single value and its count. This works well for data with repeated patterns.
What would 0000011100000011 become in RLE?
5 0 3 1 6 0 2 1.
what is lossy compression
Reduces file size by permanently removing some less noticeable data
what is lossless compression?
Reduces file size without losing any information (e.g., ZIP, PNG, FLAC).
