Representing Images, Sound and Other Data Flashcards
Describe Analogue Data
Continuous
No Limits to the values that the data can take
Can be changed as frequently as required
Smooth curves which feature sharp peaks
Describe Digital Data
Discrete
Can only take particular values
Can only take one of a specific range of values
Can only change values at specified intervals
What does a DAC stand for
Digital to Analogue converter
How does a DAC work
It reads a bit pattern representing an analogue signal and outputs an alternating, analogue, electrical current
What outputs an analogue signal
Temperature sensors and microphones
What does ADC stand for
Analogue to Digital Convertor
How does an ADC work
Takes a reading of an analogue signal at regular intervals
Records the value through sampling
Samples are taken at a specific frequency
Once the signal is recorded - it can be stored digitally as a bit pattern representing its amplitude
What are bitmap graphics and how do they work ————
A way a computer can represent an image
An image is broken down into pixels - each pixel is assigned a binary value
How is the resolution of an image represented ———–
Number of dots per square inch
OR
Number of pixels in an image
How big is a dot ——
A pixel
What determines the colour of a pixel ————–
The binary value assigned to it
What is the colour depth —————-
Number of bits assigned to a pixel in an image
How do you calculate the storage required to represent a bitmap image and what does this method tell you ————
Resolution x Colour Depth
Minimum amount of bits required due to the files containing metadata
What do vector graphics represent and how and what are the properties stored in ————–
Images using geometric objects and shapes
A list
Why can vector graphics be scaled without losing quality ———–
They use shapes instead of pixels
Uses for Vector Graphics ————
Simple images such as company logos
Uses for bitmapped graphics ————
Storing photos
Why do vector graphics frequently use less storage space than bitmapped graphics ———————
Information is stored for each shape rather than for every single pixel
How do computers represent sound
As a sequence of samples
What does a sample take
Discrete digital values
What is the sampling rate
Number of Samples per second
Measured in Hz
What is the sample resolution
Number of bits allocated to each sample
What comes with higher sample resolutions
Greater audio quality and increased file size
How can the size of a sound sample be calculated
Sample rate x sample resolution x length of sample
