2.6 Data Representation Flashcards
What is Denary?
It is the decimal number system that we are used to
What is Binary?
0 and 1’s.
What is the purpose of Hexadecimal numbers?
Provide a human-friendly representation of binary-coded values
What is an Overflow error?
When the total amount does not fit in 8 bits
What is the effect of a binary shift to the left?
Multiplies the number by 2
What is the effect of a binary shift to the right?
Divides the number by 2
What are Character sets?
A table of data that links a character to a number
What is ASCII?
Is a character encoding standard for electronic communication
How many bits are in each character of ASCII?
Each character is represented by a 7-bit number
How many bits are in each character of extended ASCII?
Each character is represented by an 8-bit binary number
How many bits are represented in each letter of Unicode?
Each letter is represented by a 16-bit
What are the benefits of using Unicode?
This gives at least twice as many character options as ASCII
Allows the character set to represent characters and symbols from all languages.
What are images made up of?
Images are made up of pixels
What is the color of a pixel represented by?
A binary number
How many colors will there be in an image which uses 1 bit?
2 colors
How many colors will there be if an image uses 2 bits for each color?
4 colors
What is color depth?
The number of bits used for each pixel
What is Resolution?
How many pixels are in a certain space
What is the effect of increasing the resolution of an image?
It increases the image quality
Increase file-size
What is Metadata?
The information about the image file that is stored within it
What are 3 examples of Metadata?
Height Width Color depth Resolution File format Data and time of the creation
What is the purpose of sampling?
Allows analogue signals to be converted into digital signals so that it can be stored on a computer
How does sampling work?
The amplitude of the wave is measured at regular intervals which creates a digital representation
More samples would lead to a more accurate sound file but leads to a larger file size
Why is compression used?
Used to make the file-size smaller
What are the advantages of compression?
This leads to data being sent faster and being downloaded quicker
Takes up less storage space
What is Lossy compression?
Permanently removes some of the data from a file
What can lossy compression do?
Can decrease the resolution of an image so there will be a lower quality than the original
What is Lossless compression?
Data is temporarily removed from the file
Put back together when it is opened
What is bit depth?
Number of bits used to record each sample
What is bit rate?
A measure of how much data is processed for each second of sound
How is the bit rate calculated?
Sample rate x bit depth
What is the difference between bit depth and bit rate?
Bit depth refers to the number of bits used to record each sample. Bit rate is a measure of how much data is processed for each second of sound.
How can an image be compressed?
Reducing its color depth
What types of files is lossy suitable for?
JPEG - Standard image file format
MPEG - Standard video file format
MP3 - Standard audio file format which uses lossy
Why type of files do we not want to lose data from?
text files
spreadsheets
financial records
emails
What type of files is lossless suitable for?
PDF - Text document
GIF - Image file
