Photopic vision means vision under light-adapted conditions. Standard photometry here uses the photopic luminous efficiency function; scotopic vision uses a different weighting for dark-adapted conditions. The response function and adaptation conditions must be stated when comparing luminous fluxes.[ref]
Mise en pratique for the definition of the candela and associated derived units for photometric and radiometric quantities in the SI. §3.1, printed p. 3: photopic and scotopic luminous efficiency functions
Photopic vision refers to the vision that occurs under well-lit conditions, enabling humans and many animals to perceive the environment in bright light. This type of vision is primarily mediated by cone cells in the retina, which are responsible for color detection and high visual acuity. In photopic conditions, the cones are activated, allowing for detailed color vision and the ability to see fine details.
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