img制图技巧：给img图片添加背景颜色和背景图片，制作出新图片
设想一个问题：如果前端页面中图片加载失败，是直接加载另一张异常图片吗？（我的答案，不完全是）
那么在这里就分享一个更加优化的技巧来处理异常图片：
效果图：
直接上代码：
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title></title>
<style type="text/css">
.img {
width: 200px;
height: 200px;
}
.img-error {
background: #f2f2f2 url(data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAC4AAAAiAQMAAAAatXkPAAAABlBMVEUAAADMzMzIT8AyAAAAAXRSTlMAQObYZgAAAIZJREFUCNdlzjEKwkAUBNAfEGyCuYBkLyLuxRYW2SKlV1JSeA2tUiZg4YrLjv9PGsHqNTPMSAQuyAJgRDHSyvBPwtZoSJXakeJI9iuRLGDygdl6V0yKDtyMAeMPZySj8yfD+UapvRPj2JOwkyAooSV5IwdDjPdCPspe8LyTl9IKJvDETKKRv6vnlUasgg0fAAAAAElFTkSuQmCC) no-repeat center center;
}
</style>
</head>
<body>
<img class="img img-error" src="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAABAQMAAAAl21bKAAAAA1BMVEUAAACnej3aAAAAAXRSTlMAQObYZgAAAApJREFUCNdjYAAAAAIAAeIhvDMAAAAASUVORK5CYII=">
</body>
</html>