LOL! "Alpha-channel" is a sort of "hidden" channel, used in masks and such like. It is a grey-scale image, and acts as a filter, controlling how much of an effect is applied, according to the lightness/darkness of the alpha. (It depends on your app as to whether white or black is max, but once you figure that out the rest is easy. To figure it out, create a mask, fill the alpha-channel with a grey-scale gradient, apply a strong effect and see what the effect is, where it affects most and least.) "Saturation" refers to how close to the primary colours a specific colour is. Fully saturated colours use almost pure primary colours; de-satuartion means moving the colours towards the grey-scale; fully de-saturated colours ARE grey-scale. Hope that helps - and good luck with your exam:-)) BTW - that is just my imperfect, layman's understanding of the subjects; I suspect that there's loads of people here who can give you better, more definitive answers; also, I think there's a 2D forum here at 'rosity - asking there would certainly elicit some answers...:-)) Cheers, Diolma