Data Representation Flashcards
How is a vector graphic represented?
Vector images are composed of objects
Properties of objects are stored
What are some properties a vector graphic might store?
Fill colour
Outline colour
x and y coords
Outline width
Width
Height
What is run length encoding?
A run is a series of pixels of the same colour.
Pairs of values are stored:
The colour and the number of pixels in the run
What is an ordinal number?
An ordinal number is used to show position/rank.
What are advantages of vector graphics?
Individual parts of images can be manipulated independently.
Parts of the image can be enlarged without loss of quality.
If component is deleted the software knows what is behind it.
Stored images take up less storage.
What are advantages of bitmaps?
Images can be represented with complex textures.
Can represent non-regular shapes.
Digital photos are naturally represented as bitmaps.
How does MIDI represent digital music?
Music is represented as a sequence of MIDI (event) messages.
Data contained in a message might include:
- Instrument.
- Frequency of note.
- Duration.
- Volume.
What are the advantages and disadvantages of MIDI?
Pros:
- Less storage space take up than sampled recording.
- Performance data can be easily manipulated (pitch, duration etc.)
Cons:
- Synthesised sound often doesn’t sound realistic.
What is analogue data (sound)?
Data measured in a continuous manner.
An electrical analogue signal consists of a continuously variable voltage.
What is digital data (sound)?
Sets of distinct values.
A digital signal is a representation of discrete values over time.
How does an ADC work?
Analogue to Digital Converter.
Analogue signals sampled at regular intervals.
Amplitude at each sample point is measured.
Measurement is coded into binary.
What is the main advantage of floating point representation?
It can represent a wider range of numbers (than fixed point)
What is an advantage of fixed point representation of a number?
Can represent numbers more precisely.
Represents numbers to a constant level of precision.
Calculations can be performed quicker.
Why are advantages of JSON over XML?
JSON is easier for humans to read.
It is more compact, uses less memory.
It is quicker to parse.
What are advantages of XML over JSON?
It allows a schema to be written. This allows the user to specify the structure of the file.
