Painting I / Colour as Pigment and Colour as Light
Practice question · Estimate

A Munsell value 5 grey looks halfway between black and white. What percentage of the light falling on it does it actually return?

Estimate on a scale from 0 per cent (0) to 60 per cent (60).

Hints
  1. The eye's response to luminance is strongly compressive.
  2. It is much less than half.
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20 (answers within ±5 count)

Why

About 20 per cent. Halfway in appearance is nowhere near halfway in physics, because the visual system compresses a huge range of luminance into a manageable scale of lightness. That gap is why a photographic grey card sits near a fifth reflectance and not a half.

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