1.2.4 Audio + Visual Formats And Compression Flashcards
What are images saved electronically made up of?
Series of pixels
What generates detail?
Changing colour or brightness of each pixel
How can images be converted into binary?
Binary code to represent each pixel
How many colours does a 1-bit image have?
Two
0 or 1
How many colours does a 2-bit image have?
Four colours
00, 01, 10, 11
How can more colours be added?
Longer binary codes
What is colour depth?
Number of bits per pixel
How many colours does a 4-bit image have?
16
What colour depth do modern devices use?
24-bit
16,777,216 colours
What makes higher resolution?
More pixels
How is an image file size determined?
Size in pixels
Colour depth
What does metadata include?
Technical data generated by camera = image properties, shutter speed, resolution, GPS location, date and time
Data added manually buy the user = places, names or captions, comments or people’s names or copyright information
What is metadata?
Information stored within the same file
How is live sound recorded?
Microphone
What is live sound called?
Analogue sound
What is Sampling
To store sound on a computer, it must be converted to digital file and stored as binary
Sample rate
Number of samples taken each second
What happens if the sample rate increases?
Quality of sound file does
Bit depth
Number of bits used to encode the sample
What is recording duration measured in?
Seconds
Data compression
Used to reduce large files
What are the benefits of data compression?
Storage space required on mobile devices and home computers can be reduced
Smaller files can be uploaded and downloaded more quickly
Limits placed on file sizes by streaming and email services can be avoided
What is lossy compression?
Removes data (duplicated elements) to create a smaller file size.
What happens to data removed during compression?
Removed permanently
What are file types for lossy compression?
JPEG, MP3, MP4, and GIF
What is lossless compression?
Uses software algorithms to compress data but then reconstructs it to its original form, preserving original file
What are the file types of lossless compression?
RAW, WAV, TIFF, BMP
How do you calculate text file?
Bits per character x number of characters
How do you calculate sound file?
Duration (s) x samples rate x bit depth
How do you calculate image file size?
Image height x width (pixels) x colour depth
