Lighting & Material Interactions Flashcards

A color expert recommends testing paint samples at multiple times of day before final selection. The primary reason is:

Answer: Natural daylight shifts in color temperature from warm (morning/evening) to cooler (midday), altering perceived hue

Solar color temperature varies from approximately 2000K at sunrise/sunset to 5500–6500K at midday, significantly affecting how wall colors appear throughout the day.

Which surface material would be most susceptible to 'bronzing,' an effect where a color looks different in specular reflection versus diffuse reflection?

Answer: Highly saturated deep-hue printed ink on glossy paper

Bronzing occurs with dense, high-chroma inks on glossy substrates where specular reflection creates a metallic sheen different from the intended color viewed diffusely.

Fluorescent colors appear to 'glow' because they:

Answer: Absorb UV or short-wave visible light and re-emit it as longer-wavelength visible light, exceeding normal reflectance limits

Fluorescent materials exhibit luminescence, converting absorbed UV or blue light into longer-wavelength emissions that push their reflectance above 100% relative to a non-fluorescent white.

An architect specifies a warm-white wood veneer for a lobby. Under the cool-white LED fixtures (6000K) installed, the veneer appears grayish. The best corrective action is:

Answer: Replace or supplement with warmer CCT lighting (2700–3000K) more appropriate for the material

Warm materials like natural wood are best rendered by warm-CCT light sources; cool sources shift the appearance toward gray by emphasizing the wood's achromatic qualities.

The concept of 'Gamut Mapping' is most directly applied when:

Answer: Translating colors from one color space (e.g., display RGB) to another with a smaller gamut (e.g., CMYK print)

Gamut mapping algorithms compress or clip out-of-gamut colors to fit within the target device's reproducible color space while minimizing perceptual distortion.

A color expert evaluating a paint chip under a light booth notices the color shifts significantly between the D65 and the Incandescent (A) illuminant positions. This indicates:

Answer: The paint sample exhibits noticeable metamerism and should be matched under the intended end-use illuminant

A large color shift between illuminants in a light booth indicates the sample is metameric, meaning its acceptability must be judged under the actual lighting conditions of the end-use environment.

Retroreflective materials used in safety garments appear very bright when a light source is close to the observer's line of sight because:

Answer: Microscopic glass beads or prisms reflect light directly back toward the light source, regardless of incidence angle

Retroreflective materials use glass microspheres or cube-corner prisms to redirect incident light back along the path it came from, making them extremely visible when illuminated from the viewer's direction.