Rainbows are Harmful

Rainbow color scales are harmful. Please use a perceptually-optimized color scale instead.

<!DOCTYPE html>
<meta charset="utf-8">
<body>
<script src="//d3js.org/d3.v3.min.js"></script>
<script>

var width = 960,
    height = 500;

var color = d3.scale.linear()
    .domain([0, 255])
    .range(["hsl(0,80%,50%)", "hsl(360,80%,50%)"])
    .interpolate(d3.interpolateString);

var canvas = d3.select("body").append("canvas")
    .attr("width", width)
    .attr("height", height);

var context = canvas.node().getContext("2d");

getImage("readme.png", function(error, image) {
  if (error) throw error;
  context.drawImage(image, 0, 0, width, height);
  image = context.getImageData(0, 0, width, height);

// Rescale the colors.
  for (var c, i = 0, n = width * height * 4, d = image.data; i < n; i += 4) {
    c = d3.rgb(color(d[i]));
    d[i + 0] = c.r;
    d[i + 1] = c.g;
    d[i + 2] = c.b;
  }

context.putImageData(image, 0, 0);
});

function getImage(path, callback) {
  var image = new Image;
  image.onload = function() { callback(null, image); };
  image.onerror = callback;
  image.src = path;
}

</script>

https://d3js.org/d3.v3.min.js