Vision and Color – Quick Notes

Light is a spectrum of electromagnetic energy; humans detect only a small portion, enabling perception of color.
Hue is determined by wavelength; brightness (value) and saturation affect how light is perceived.
Color labeling is a convention, not a physical property; without light there is no color, only darkness.
Digital color is described by codes (e.g., hex codes) rather than actual color names; names are labels, not intrinsic properties.
If we turn on all lights, the hue remains the same, but perceived brightness changes.

Key parts: cornea, iris, pupil, lens; light enters and is focused onto the retina.
Retina contains cones (color) and rods (black/white/gray).
The eye is concave; images on the retina are inverted.
Common vision differences: near-sighted (myopia) and far-sighted (hyperopia); glasses help adjust focus.
Light adaptation: pupils and lenses adjust to brightness; sudden light can cause temporary blindness or afterimages.

Trichromatic theory: three cone types (red, green, blue) enable perception of all colors; printers use primary colors to reproduce images.
Monochromacy/Dichromacy: varying degrees of color perception depending on number of functional cone types.
Opponent-process theory: color receptors respond in opposing pairs; explains afterimages and color contrasts.
Color vision deficiencies: color blindness varies; some people have difficulty distinguishing certain colors (e.g., reds and greens).

Colors carry cultural and emotional associations (e.g., red can connote danger or intensity in some contexts).
Afterimages: prolonged staring causes a perceived image of complementary colors when looking away.

Closure: fragmented parts seen as a whole.
Figure-ground: separating object from background; multiple possible interpretations.
Proximity and grouping: elements near each other are perceived as a pattern or unit.
Perception is shaped by context, prior knowledge, and processing strategies in the brain.
Depth perception: cues such as shading, size, and context affect how we perceive depth; small changes can alter perceived color/size in an image.

Key terms: hue, saturation, value (brightness); wavelength determines hue.
Cone types drive color vision; rods handle luminance.
RGB (red, green, blue) model; primary colors used in additive color mixing; printers often use CMY in subtractive mixing.
Color labeling vs. wavelength: hex codes name colors in digital media, not the physical property itself.
Expect variability in color perception across individuals; accuracy can depend on lighting, adaptation, and viewing context.