JSFiddle - React, Tailwind, and code Playground

HTML

<canvas id="c"></canvas>

JavaScript

var ctx = document.getElementById('c').getContext('2d'),
    xhr = new XMLHttpRequest();

xhr.open('GET', 'http://chovy.dyndns.org/cdn/16907303_1294527306.jpg');
xhr.overrideMimeType('text/plain;charset=x-user-defined');
xhr.onreadystatechange = loaded;
xhr.send();

function loaded() {
    if (xhr.readyState != 4) return;
    var resp = xhr.responseText;
    
    var data = 'data:';
    data += xhr.getResponseHeader('Content-Type');
    data += ';base64,';
    
    var decodedResp = '';
    for(var i = 0, L = resp.length; i < L; ++i) {
        decodedResp += String.fromCharCode(resp.charCodeAt(i) & 255);
    }
    
    data += btoa(decodedResp);
    
    var img = new Image(data);
    img.onload = function() {
        ctx.drawImage(img, 0, 0);
        var pixels = ctx.getImageData(16, 17, 1, 1).data;
        alert(pixels[0]);
    };
    img.src = data;
}