輝度 is read as きど (kido) and means brightness.
きど
kido
きどしんごう
luminance signal
こうきど
high luminance (used to describe bold-face text on display screen)
かがやかしい
brilliant
かがやく
to light up (with happiness, hope, etc.)
かがやき
brightness
かがやかす
to light up
かがやくじょせい
women who excel
きせきあんざんがん
pyroxene andesite
たいど
attitude (towards an issue, etc.)
みつど
density
いど
latitude (nav.)
せつど
moderation