But how much brighter is green light really? (compared to Red, or Blue)

[djozz]

Because that function from wikipedia does not show a grid, I wrote this post a while ago:

V(lambda) curve

When thinking about light output and in discussions I regularly feel the need to refer to this V (lambda) luminosity curve, that describes the relative sensitivity of the human eye for the different colours of light, as a fraction of the sensitivity to 555nm for which the eye is most sensitive. The V (lambda) function is also integral to the lumen unit, which takes the different sensitivities for different wavelengths into account. For example, recently when I tested the output (in lumen) of a …