Code
<canvas id="canvas" width="500" height="400" style="background-image: url('535px-Floor-stone_02.JPG'); border: 1px solid #000000;"></canvas>

<script type="text/javascript" language="javascript" charset="utf-8">
    var canvas = document.getElementById('canvas');
    var context = canvas.getContext('2d');
    context.fillStyle = '#FFFFFF';
    context.fillRect(65, 50, 370, 300);
    context.fillStyle = 'rgba(0, 0, 0, 0.008)';

    for (var i = 0; i <= 30; i++) {
        setTimeout(function() {
            context.fillRect(125, 100, 250, 200);
        }, 80*i);
    }
</script>