bear (xgl99@xxxxxxxxxxxxxxxxxxxxx) wrote: > Assume there are four layers, all of which are in Normal mode and grayscale. > for a specific pixel in each layer, > Their intensity and alpha values(mapped to [0,1]) are > i1,a1 > i2,a2 > i3,a3 > i4(background) > > the merged intensity is ((i1*a1+i2*(1-a1))*a2+i3*(1-a2))*a3+i4*(1-a3) > am I correct? Thanks! Yes. You might want to look for the paper T. Porter & T. Duff - Compositing Digital Images for an explantation and the reasoning behind these rules. The paper itself is available at e.g. http://keithp.com/~keithp/porterduff/ Bye, Simon -- simon@xxxxxxxx http://simon.budig.de/
