astr-1101

cpsc-1480

- Chapter 3 reading
- Lecture outcomes
- Distinguish analog vs digital
- Explain compression and calculate compression ratios
- Do text compression
- Explain the nature of sound
- Explain how RGB define color
- Distinguish between raster/vector graphics Todo
- Explain temporal/spatial video compression

- Data
- Values or facts
- Can be unstructured
- Lack context
- All data is stored as binary digits (bits)

- Information
- Data organized and/or processed in a way that is useful in solving some kind of problem

- Analog vs digital
- Analog --> infinite
- Continuous representation
- Analogous to actual information it represents

- Digital --> finite
- Computers are limited by memory
- Represent
*enough* of the world to satisfy computational needs and our senses
- Discrete representation
- We can only represent data with
`0`

s and `1`

s

- Breaks up information in separate elements

- Electronic signals
- Analog signal continually fluctuates in voltage
- Digital signal has only high or low state
- Corresponds to two binary digits

- All electronic signals degrade as the move
- Voltage signal fluctuates due to environmental effects

- Audio information
- Digitized by:
- Sampling --> periodically measure the voltage
- Quantization --> represent voltage as a number using finite number of bits

- Color depth