   ctx.clearRect 0, 0, width, height
   ctx.globalCompositeOperation = 'source-over'
 
+  if L == 0 or L == 100
+    return
+
   xn = width / dim
   yn = height / dim
 

    .attr("cx", 0)
    .attr("cy", 0)
    .attr("r", 4)
    .attr("transform", "translate(200, 200)")
    .attr("fill", "none")
    .attr("stroke-width", 2)

    redrawSwatch()

sliderLightness = d3.slider()
  .min(0)
  .max(100)
  .on 'slide', (e, value) ->
    L = value
    background.redraw()
