canvas.html

<!DOCTYPE html>
<html>
<head>
    <title>Get Average Color for canvas</title>
    <meta charset="utf-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1, maximum-scale=1" />
    <link rel="stylesheet" href="dist/canvas.css" />
    <script src="dist/canvas.js" async></script>
</head>
<body>
    <canvas width="640" height="480" ></canvas>

    <div class="info">Average color:
        <div class="info__color"></div>
        <div class="option">
            Algorithm:
            <label><input name="algorithm" type="radio" id="algorithm-simple" autocomplete="off" checked /> simple</label>
            <label><input name="algorithm" type="radio" id="algorithm-sqrt" autocomplete="off" /> sqrt</label>
            <label><input name="algorithm" type="radio" id="algorithm-dominant" autocomplete="off" /> dominant</label>
        </div>

        <div class="option">
            Mode:
            <label><input name="mode" type="radio" id="mode-precision" autocomplete="off" checked /> precision</label>
            <label><input name="mode" type="radio" id="mode-speed" autocomplete="off" /> speed</label>
        </div>

        <div class="option">
            Step: <input id="step" value="1" type="number" size="2" min="1" max="20" />
        </div>

        <div class="option">
            Size:
            <label><input name="width" type="radio" id="width-640" autocomplete="off" checked /> 640×480</label>
            <label><input name="width" type="radio" id="width-1280" autocomplete="off" /> 1280×1024</label>
            <label><input name="width" type="radio" id="width-2560" autocomplete="off" /> 2560×2048</label>
        </div>

        <button id="start">Stop</button>
    </div>
</body>
</html>