Unit 1 Flashcards
Formula for file size in an image
Image resolution x colour depth
Define bitmap image
Image made of 2-D matrix of pixels
Define pixel
Smallest element used to make an image (single element of bitmap image)
Define colour depth
The number of bits used to represent the colours of a pixel
Define screen resolution
Total number of pixels on a screen (HxL)
Define Image resolution
Total number of pixels per inch in an image
What is the relationship between image quality and colour depth and image resolution?
If you increase colour depth or/and image resolution, the image quality increases
What is the relationship between file size and colour depth and image reoslution?
If you increase colour depth or/and image resolution, the file size increases
Define sampling rate
how many samples are collected in 1 second
Define sample resolution
How much memory (bits) needed for 1 sample
Formula for file size in an audio
Sample rate x Sample resolution x Length of audio
Sample rate units
Hz (hertz)
Sample resolution units
Bits
File size units in an audio
Bits
Define Lossy compression
If you compress and file, you lose some portion of it (portion of file is lost) (lose samples, colour depth, pixels, etc…)
Define Lossless compression
If you compress a file, you lose nothing. When you decompress the file, you get everything back (Nothing is lost when file is compressed)
Is audio compression lossy or lossless?
lossy compression
In what ways is audio compressed?
-Take away samples (reduce sample rate)
-Reduce sample resolution
-Cut frequency (Hz) lower and higher than human hearing range (remove frequency out of range)
-If there is a smaller, similar sound, get rid of it because you can’t hear it anyways (remove softer sound)
What is compressing audio called?
Perceptual music shaping
Is video compression lossy or lossless?
Lossy compression
In what ways can you compress a video?
-reduce quality
-compress all audio (reduce sampling rate and sample resolution
-reduce the number of frames
-reduce pixels on frames
-reduce frame rate
Is image compression lossy or lossless?
Lossy compression
In what ways can you compress an image?
-Crop image (remove part of image)
-Reduce colour depth
-Reduce bit depth
-Reduce image resolution
Define run-length encoding
Encoding running characters. A lossless file compression technique used to reduce the size of text and photo files in particular
Is run-length encoding lossy or lossless compression?
Lossless compression
What is the order of Denary Units from smallest to biggest?
bits -> bytes -> KB -> MB -> GB ->TB -> PB
What is the order of Binary Units from smallest to biggest?
bits -> bytes -> KiB -> MiB -> GiB -> TiB -> PiB
By how much does Binary Units increase by?
1024 (2 to the power of 10)
By how much does Denary Units increase by?
1000 (10 to the power of 3)
By how much does Hertz increase by?
1000 (10 to the power of 3)
What is the order of Hertz from smallest to biggest?
Hz -> KHz -> MHz -> GHz -> THz -> PHz
What is the safe method for converting units in audio?
Sample Rate -> Hertz (Hz)
Sample Resolution -> Bits
Time -> Seconds
What is the relationship between audio quality and sample rate and sample resolution and file size?
If the sample rate and/or sample resolution increases, the audio quality increases and the file size increases
What is 30 frames per second?
30 colours showed in a second in a single pixel
What is the relationship between pixel number and image quality and file size?
If the number of pixels increases, the image quality increases and the file size increases
How many bits is 1 byte?
8
Define information
Processed data (look at data and generate it)
Define data
Raw. Just there. (Images, videos, audio, text)
Do you use lossy or lossless compression when compressing a text file?
Lossless compression
If you know the upper case letter, how do you find the lower case letter?
Add 32
When shifting does not work out, what is it called?
An error as the numbers overflowed. Not enough space in the register to store this data. OVERFLOW ERROR
When you shift to the left 3 times, how many times is the number multiplied?
8
When you shift to the right 2 times, how many times is the number divided?
4
When you increase the unit (KB/KiB), do you divide or multiply?
divide
Define bit
Binary digit
Give 2 reasons why computers use binary numbers rather than denary numbers
Computer circuits are made up of switches/transistors
that can be on (1) or off (0)
Give 3 reasons why it is necessary to reduce the size of a file
-Save storage
-Reduce file size to be able to send it
-Faster to upload/download file
Explain the difference between lossy and lossless file compression
Lossless compression can be reconstructed to the original file when its uncompressed but lossy compression cannot be reconstructed to the original file once it has been compressed
Explain the difference between ASCII code and Unicode
ASCII code is a 7-bit code that has 32 control characters and is found in the standard keyboard. there is also an Extended ASCII code that uses a 8-bit code for non-english users. It also uses 1 byte for 1 character. Unicode represents all languages and the first 128 characters are the same with ASCII code but Unicode can support thousands of more different characters. It also uses 4 bytes for 1 character
In a binary number, what is the right most bit called?
Least significant bit
In a binary number, what is the left most bit called?
Most significant bit
What is shifting binary numbers called?
Logical shift
Define ASCII code
7-bit code character set used to represent all characters found on a standard keyboard and 32 control codes
Define Unicode
A character set which represents all the languages of the world (the first 128 characters are the same as ASCII code) It also uses 4 bytes for 1 character
How does lossless compression compress a text file?
A compression algorithm called Run length encoding is used and any repeating words/characters/phrases/patterns are identified and indexed with their number of occurrences and their position
What are temporary files where no compression has been applied called?
Raw bitmap files
How are texts converted to binary to be processed by the computer?
Each character has a unique binary value so a character set is used such as Unicode or ASCII code and then converted.
How is a file compressed using lossless compression?
Repeated words/patterns are indexed and replaced with numerical values. No data is lost in the process
1 example of the use of lossless file compression
Run length encoding
1 example of the use of lossy file compression
Mpeg3
What are 2 benefits using hexadecimal instead of binary values?
-Easier to debug
-Easier to represent
