Computer Science: Data Encoding, Compression, and Python Basics

All data is represented by...

Numbers

Encoding

The process of assigning numbers to data

Compression

Methods used to reduce data size

Lossless compression

No data is lost; original can be perfectly reconstructed

Lossy compression

Some data is lost to make the file smaller

Run-Length Encoding (RLE)

A lossless compression method that stores repeated values as value + count

ASCII

A standard numerical encoding for letters and symbols

RGB color model

Colors are assigned using Red, Green, and Blue values

JPEG

A lossy image compression format

PNG

A lossless image compression format

BMP

A basic uncompressed image format

Metadata

Data about data (e.g., creation date, file size)

Steganography

Hiding information inside another file, like an image

Parity

The evenness or oddness of the number of 1s in binary

Parity bit

A bit added to data to make the total number of 1s even or odd

Even parity

The total number of 1s must be even

Odd parity

The total number of 1s must be odd

What parity bits are used for

Error detection

Steps to developing code

Design → Code → Test → Debug → Refine

Python input command

`input()`

Python output command

`print()`

Variable

A name that stores a value in memory

Guidelines for naming variables

No spaces, descriptive names, start with a letter

Assigning a variable

`x = 5`

Arithmetic operators

`+ - / // % *`

Comparison operators

`== != > < >= <=`

Logical operators

`and or not`

If statement syntax

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