#Colour Density Grid Dots are placed randomly, then they are grouped by the grid. The tile colour is determined by the dot density. Raster is a grid.
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<html lang="en">
<head>
<meta charset="utf-8">
<title>Colour Density Grid</title>
<script src="https://cdnjs.cloudflare.com/ajax/libs/d3/3.5.6/d3.min.js" charset="utf-8"></script>
</head>
<body>
<div id="chartArea"></div>
<script src="js.js"></script>
</body>
</html>
https://cdnjs.cloudflare.com/ajax/libs/d3/3.5.6/d3.min.js