diff --git a/libs/gfx/include/psemek/gfx/color.hpp b/libs/gfx/include/psemek/gfx/color.hpp
index 7bec7f28..b4d01a28 100644
--- a/libs/gfx/include/psemek/gfx/color.hpp
+++ b/libs/gfx/include/psemek/gfx/color.hpp
@@ -382,6 +382,12 @@ namespace psemek::gfx
 		return result;
 	}
 
+	template <std::floating_point T, std::size_t N>
+	T luminance(math::vector<T, N> const & c)
+	{
+		return c[0] * T(0.299) + c[1] * T(0.587) + c[2] * T(0.114);
+	}
+
 	std::optional<color_rgba> parse_color(std::string_view const & text);
 
 }