Images and Sound Flashcards
What does PIXEL stand for?
Picture Element
PIXEL is short for ‘picture element’, the smallest unit of a digital image.
What is the typical resolution of a 13-inch monitor?
640 pixels horizontally and 480 pixels vertically
What are the primary colors used in the RGB model?
Red, Green, Blue
What is the term for the amount of memory dedicated to each screen pixel?
Colour depth
How many colors can a 1-bit display system manage?
2 colors (black or white)
How many unique colors can an 8-bit display show?
256 colors
What is a True-colour or 24-bit display capable of showing?
Millions of unique colors
What is the formula for calculating the total number of colors in a 24-bit display?
8 bits for red + 8 bits for green + 8 bits for blue = 24 bits
What is the difference between bitmap and vector images?
Bitmap images are stored as a grid of pixels, while vector images are stored as geometrical shapes defined by specific properties
Name two popular graphics formats for bitmap images.
- JPG
- GIF
What are the advantages of vector images?
- Does not deteriorate when enlarged
- Uses less memory
- Easier to edit/manipulate
What must be done to convert sound into digital form?
Use an analogue-to-digital converter (ADC)
What is Pulse Code Modulation (PCM)?
A technique to convert an analogue signal into a digital signal by sampling at fixed intervals
What is the Nyquist rate?
The sampling rate should be at least twice the maximum frequency of the sound wave to avoid loss
What is MIDI?
A sequence of event messages that can synthesize musical notation
What information is stored in a MIDI file?
- Length/duration of note
- Instrument
- Velocity
- Volume
- Timbre
- Pedal effects
- Channel
What is the sampling rate required for CD quality sound?
44,000 samples per second (44 kHz)
What is audio compression?
The process of minimizing storage space/bandwidth requirements for audio data
Differentiate between analogue sound and digital sound.
Analogue sound is continuous, while digital sound is discrete and stored in binary form.
What are the two parts of audio compression?
- Encoding
- Decoding
What does a 16-bit sound card represent?
65,536 sound levels
What is the significance of recording a stereo sound?
It doubles the number of samples needed per second
What is the file size formula for sound?
Sampling Rate x BitRate x No. of seconds
What does the term ‘quantisation’ refer to in PCM?
Approximating the height of each PAM pulse by an n-bit integer
