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Photometry Luminance and Illuminance units vs. Radiometry Radiance and Irradiance units
Photometry Luminance and Illuminance units vs. Radiometry Radiance and Irradiance units
Photometric Terms:
Light sources that illuminate test charts reflectively are typically described in terms of Photometric units that are comparable to the response of the human eye or an image sensor that has a spectral response similar to the human eye (such as a silicon sensor with a near-IR cutoff filter).
Candelas measures light intensity in a specific direction
Luminance measures the luminous intensity per unit area of light traveling in a given direction
Illuminance measures the total light falling on a surface: