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

[Simon Budig <simon budig de>]

Calculemus (calculemus1988 gmail com) wrote:
> I am reading this: docs.gimp.org/en/gimp-concepts-layer-modes.html
> 
> 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?

for 8 bit modes 255 is equivalent to the value 1.0. So the proper
formula would be

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

I guess you can see how the other formula happens then   :-)

Bye,
        Simon

-- 
              simon budig de              http://simon.budig.de/