The next effect is something easy: a grayscale shader. It supports 8 different modes. This shader is also a nice example how to use the .technique feature of Gamestudio The download link is in the first post of this thread.

Grayscale shader:


P.S: if you use an alpha below 0%, you BOOST your colors by their calculated luminance and if the alpha is above 100%, the colors get INVERTED and are boosted if above 200%!