Data Storage & Compression Flashcards
How many bits are in a byte?
8 bits.
How many bytes are in a Kibibyte?
1024 bytes
What is the difference between a megabyte and a mebibyte?
A megabyte is 1000 squared bytes, while a mebibyte is 1024 squared bytes.
True or False?
When converting between units larger than a byte, we use multiples of 1000.
False.
When converting between units larger than a byte, we use multiples of 1024 (2^10).
What is a Tebibyte?
1,099,511,626,776 bytes (2^40 bytes).
How do you convert from bytes to bits?
multiply by 8.
How do you convert from kibibytes to bytes?
multiply by 1024.
What is the formula for calculating the size of a bitmap image?
Resolution x color depth
or
Image width x image height x color depth
True or False?
A color depth of 24 bits is equal to 3 bytes.
True.
A color depth of 24 bits is equal to 3 bytes.
What is the formula for calculating the size of a sound file?
Sample rate x duration x sample resolution.
Define sample rate.
Sample rate is the number of samples taken per second in a digital audio recording.
Define sample resolution.
Sample resolution is the number of bits stored per sample in a digital audio recording.
How do you convert file size from bits to bytes?
divide by 8
How do you convert file size from bytes to kibibytes?
divide by 1024
Define compression
Compression is reducing the size of a file so that it takes up less space on secondary storage.
State three benefits of compression.
- Less storage space required
- Less bandwidth required
- Shorter transmission time
Define lossy compression.
Lossy compression is a method of data compression where data is lost in order to reduce file size, resulting in a loss of quality but smaller file sizes.
Define lossless compression.
Lossless compression is a method of data compression where data is encoded to reduce file size without losing any information, allowing the original data to be perfectly reconstructed.
True or False?
Lossy compression is reversible.
False.
Lossy compression is irreversible
What types of files are suitable for lossy compression?
Files suitable for lossy compression are those where reducing quality is acceptable, such as images, video, and sound files.
How does lossy compression work on photographs?
In photographs, lossy compression tries to group similar colours together, reducing the number of colors in the image without significantly compromising the overall visual quality.
True or False?
Lossless compression can be used on all types of data
True.
Lossless compression can be used on all types of data.
How does lossless compression work on documents?
In documents, lossless compression uses algorithms to analyze the contents, looking for patterns and repetition, such as replacing repeating characters with a single character and the number of occurrences.
What is the advantage of lossless compression over lossy compression?
An advantage of lossless compression is that the file can be returned to its original state without any loss of data quality.
Describe how lossless compression compresses the text file.
- Compression algorithm is used such as RLE
- Patterns are identified with their position
Give two reasons why the text file may have been compressed
- To save storage space
- To make it quicker to transmit
