X-Git-Url: https://git.sesse.net/?p=movit;a=blobdiff_plain;f=lift_gamma_gain_effect.h;h=36f6a77370461c2c66b8d6b5e60b11e298c21df4;hp=131957009a37bd35ccc954035f05a85ac03e358f;hb=c7e57f5c9fbc1b58d450557cfbffe60480bdd6b7;hpb=f99ad333a7acbb6c8c995dbb036484ae8940c490

diff --git a/lift_gamma_gain_effect.h b/lift_gamma_gain_effect.h
index 1319570..36f6a77 100644
--- a/lift_gamma_gain_effect.h
+++ b/lift_gamma_gain_effect.h
@@ -16,6 +16,9 @@
 // rest of the curve relatively little. Thus, we actually convert to gamma 2.2
 // before lift, and then back again afterwards. (Gain and gamma are,
 // up to constants, commutative with the de-gamma operation.)
+//
+// Also, gamma is a case where we would not want premultiplied alpha.
+// Thus, we have to divide away alpha first, and then re-multiply it back later.
 
 #include "effect.h"