src = "url_to_imgur"
img = new Image();
img.crossOrigin = "Anonymous";
img.addEventListener("load", analyze, false);
img.src = src;


function analyze() {
    canvas = document.createElement("canvas")
    ctx = canvas.getContext("2d")
    ctx.drawImage(img, 0, 0, img.width, img.height);
    imageData = ctx.getImageData(0,0,img.width, img.height)
    value = imageData.data.reduce((cur, i) => cur + i,0)
    result = value / imageData.data.length
    console.log(result);
}