Re: [Gimp-developer] Multiply blend mode in GIMP

Date: Mon, 9 Jul 2012 21:21:46 +0200
From: calculemus1988 gmail com
To: gimp-developer-list gnome org
Subject: [Gimp-developer] Multiply blend mode in GIMP

I am reading this:

and I wonder why is the formula for "Multiply", E = (M * I) / 255?

Why divide with 255, that is the part that confuses me.
Should it not be just M * I and then clamp the result in range 0 to 255?


_______________________________________________ gimp-developer-list mailing list gimp-developer-list gnome org

Other people have answered it already, but an alternate way of looking at the Multiply formula is:

E = M * (I / 255)
E = (M/255) * I

Where M (the multiply layer) values are expressed in a 0...255 range, therefore, (M/255) yields a 0-1.0 percentage and that is exactly the behavior we need.

The documentation could probably be phrased just a little better.

-- Stratadrake
strata_ranger hotmail com
Numbers may not lie, but neither do they tell the whole truth.

[Date Prev][Date Next]   [Thread Prev][Thread Next]   [Thread Index] [Date Index] [Author Index]