>function noiseimg () ...
$aspect(320,240); clg;
$count=0; now=time;
$repeat
$  plotrgb(intrandom(240,420,2)-1,[0,0,1024,1024]);
$  wait(0);
$  count=count+1;
$  until testkey();
$end;
$return count/(time-now);
$endfunction
>noiseimg
 2.73544353263