Physics of Light and Digital Color Models

Color theory in digital interfaces is governed by the physics of optical radiation and human photoreceptor neurology.

Additive (RGB) vs. Subtractive (CMYK) Models

• Additive Color (RGB): Digital screens emit light directly. Red, Green, and Blue sub-pixels combine additively. Combining all three at maximum intensity produces pure white (#FFFFFF), while their absence produces black (#000000).
• OLED Displays & Dark Mode: True black (#000000) turns OLED sub-pixels completely off to conserve battery. However, UI designers often use deep dark gray (e.g. #121212) for scrolling content to prevent 'OLED smearing'—a visual lag caused when pixels take a few milliseconds to wake up from a zero-voltage state.
• Subtractive Color (CMYK): Physical printing inks (Cyan, Magenta, Yellow, Key/Black) absorb and reflect ambient light. Combining all pigments produces dark muddy brown/black.

Modern Color Spaces: HSL and OKLCH

While hex codes (#513DEB) describe raw hardware values, modern UI systems favor perceptual color models:

• HSL (Hue, Saturation, Lightness): Intuitively separates chromatic tone from intensity and luminance, but lacks perceptual uniformity (e.g., yellow looks significantly brighter than blue at the same 50% lightness).
• OKLCH (Perceptual Lightness, Chroma, Hue): Guarantees uniform perceived brightness across all hues, eliminating optical lightness shifts when adjusting color tokens or generating accessible palettes.