Layout, Colour Paradigms & Character Sets

RGB (Additive): Used for digital displays, this model combines Red, Green, and Blue light. Starting from black (no light), adding all three at maximum intensity ($255, 255, 255$) results in white light.

CMYK (Subtractive): Used for physical printing, this model uses Cyan, Magenta, Yellow, and Key (Black) inks. These pigments subtract wavelengths from white light; combining them theoretically results in black.

HSL (Hue, Saturation, Lightness): A more intuitive model for human designers. Hue represents the color type (0-360 degrees), Saturation the intensity, and Lightness the amount of white or black mixed in.

Hexadecimal Codes: A shorthand for RGB values where two hex digits represent each channel (e.g., #FF0000 is pure red). This allows for $16^6$ or approximately 16.7 million possible colors.

ASCII (American Standard Code for Information Interchange): A 7-bit character set providing 128 unique codes. It covers basic English letters, digits, and control characters but lacks support for international symbols.

Extended ASCII: Uses 8 bits ($2^8 = 256$ codes) to include some special characters and accented vowels, but different 'code pages' led to compatibility issues between systems.

Unicode: The modern universal standard designed to represent every character from every writing system. It assigns a unique 'code point' to over 140,000 characters.

UTF-8 Encoding: A variable-width encoding for Unicode that is backward compatible with ASCII. It uses 1 byte for standard English characters and up to 4 bytes for complex symbols, optimizing storage efficiency.

Bit Calculations: Always remember that an $n$-bit character set can represent $2^n$ unique characters. If an exam asks for the bits needed for 500 characters, you must choose 9 bits ($2^9 = 512$) because 8 bits ($2^8 = 256$) is insufficient.

Contrast Ratios: In layout questions, prioritize accessibility. Ensure text-to-background contrast meets WCAG standards (usually 4.5:1 for normal text) to avoid losing marks on usability.

Hex to RGB Conversion: Practice converting Hex pairs to decimal. Remember that #00 is 0 and #FF is 255. A value like #808080 represents a medium gray because all channels are equal and at the midpoint.

Encoding Awareness: When discussing UTF-8, emphasize its variable-length nature. It is a common misconception that all Unicode characters take up the same amount of memory.