load image "w.jpg",1
R# = rgb(255,0,0)
G# = rgb(255,0,0)
B# = rgb(255,0,0)
do
greyscale(R#,G#,B)
SPRITE  1, 0, 0, 1
SET SPRITE DIFFUSE 1, R#, G#, B#
sync
loop

function greyscale(R#,G#,B)
 G# = (R#+G#+B#)/3
 endfunction