Code with sample:
<script Language="JavaScript"> r=0 g=0 b=0 function pset(x,y,wi,he) { document.write ("<img src='1x1.gif' style='z-index:-10; position:absolute; left:"+x+";top:"+y+";width:"+wi+";height:"+he+";background:rgb("+r+","+g+","+b+")'>") } kx=400 ky=400 x0=(window.screen.width-20)/2 y0=400 r=g=b=0 pset(x0-kx/2,y0,kx,2) pset(x0,y0-ky/2,2,ky) g=255 for(x=-kx/4;x<kx/4;x++) { y=x*x/kx*8 pset(x+x0,-y+y0,2,2) } g=0 r=255 for(x=-kx/2;x<kx/2;x++) { y=Math.sin(x/kx*20)*ky/10 pset(x+x0,-y+y0,2,2) } r=0 b=255 for(i=-100;i<100;i=i+0.5) { x=Math.cos(i/100*3.15)*kx/4 y=Math.sin(i/100*3.15)*ky/4 pset(x+x0,-y+y0,2,2) } </script>1x1.gif is a 1 pixel square transparent gif. To download a copy from this server, right click on this and select "Save as..."
For discussion, and further information about this script, see imgdraw.htm