JailBreakC

var cv = document.getElementById('cv');
var c = cv.getContext('2d');
var txtDiv = document.getElementById('txt');
var fileBtn = document.getElementById("up-button");
var img = new Image();
img.src = 'a.jpg';
img.onload = init; // 图片加载完开始转换
fileBtn.onchange = getImg;

// 根据灰度生成相应字符