Data representation Flashcards
Order the following in descending size;
Byte, Petabyte, Megabyte, Gigabyte, Nibble, Terabyte, Kilobyte, Bit
Bit (1 or 0)
Nibble (4)
Byte(8)
Kilobyte(1000B)
Megabyte(1000kB)
Gigabyte(1000MB)
Terabyte(1000GB)
Petabyte(1000TB)
Convert 73 to binary
1001001
Convert 110110 to denary
54
Convert 37 to hexadecimal
25
Convert 4F to denary
79
Convert 100111 to hexadecimal
27
convert 3C to binary
111100
2-place shift 1101100 to the right and explain the effect
11011, divided by 4
How many characters do ASCII and Unicode represent and what are their differences
ASCII - 2^7 (128), extended ASCII 2^8 (256)
Only some foreign language characters and symbols
Unicode - 2^16(65536)
Includes Chinese, Arabic, Japanese, Greek characters and more
How do you calculate colour depth
log ₂(N of colours)
State the effect on file size of changing a 4 x 4 pixel from 2 colours to 256
-Each pixel was previously 1 bit, now is 8 (byte)
-The file size would now increase to 16bytes
What is resolution
The density of pixels in the same sized area, measures in PPI. A higher PPI will mean smoother edges and improve overall quality
What is metadata and state 3 examples
Data about data, eg type of image, image dimensions or colour depty
How do computers convert real-world analogue signals, such as sound, to a digital representation
Sound is received by a microphone, then converted by a ADC (Analogue-to-Digital Converter), The ADC samples the amplitude at regular intervals which are then rounded and stored in binary.
How do you calculate the size (in bits) of an image file
Colour depth x image height x image width
What is sample rate and how does it affect sound file size and quality?
The number of samples taken a second, measured in Hz. Higher Hz means better quality but also increases file size.
What is sample resolution and how does it affect sound file size and quality?
The number of bits used to store each sample, higher SR means higher quality but also larger file size
What is a sample
A measure of amplitude at a point in time
How do you calculate the size of a sound file
Sample rate x Sample size x Sample resolution
Why are files compressed?
-Shorten transmittion time
-Reduce amount of storage needed
-Allow large files to be sent as attachments
Sort the following into lossy and lossless forms of compression: gif, mp3, mpg, mp2, mov, jpg, wmv, png
Lossy - jpg, mp3, mpg, mp2, wmv
Lossless - png, gif,mov
Explain the uses, advantages and disadvantages of lossy compression
•Music streaming, online videos and images
+Small file size = faster transmition and less storage required
-Detail permanently lost
Explain the uses, advantages and disadvantages of lossless compression
•Text documents, electronic books
+Original quality is preserved, no data lost
-Less reduction in file size
