load image "w.jpg",1
R# = rgb(255,0,0)
G# = rgb(255,0,0)
B# = rgb(255,0,0)
do
SPRITE  1, 0, 0, 1
greyscale(R#,G#,B)
if spacekey()=1
point(x+15,y+20)=G# = (R#+G#+B#)/3
endif
sync
loop

function greyscale(R#,G#,B)
R# = rgb(255,0,0)
G# = rgb(255,0,0)
B# = rgb(255,0,0)
 G# = (R#+G#+B#)/3
 endfunction