php将图片转换为base64编码字符串

周末在家做技术调研，读取一行图片并将其转换为base64字符串。
代码如下:
<!--?php
/**
 * Created by PhpStorm.
 * User: yuqingzhang
 * Date: 16/8/6
 * Time: 19:46
 */
class changeformat
{
    public function changeImageToString()
    {
        $file = "zhima/hello.jpg";
        if($fp = fopen($file,"rb", 0))
        {
            $gambar = fread($fp,filesize($file));
            fclose($fp);
            $base64 = chunk_split(base64_encode($gambar));
            echo 'str is :'.base64_encode($gambar).'<br/-->';
            //Result
            $encode = '<img src="https://zhangyuqing.cn/wp-content/uploads/2016/08/gifbase64.png' . $base64 .'" />';
            echo $encode;

        }
    }
}

$changeFormat = new changeformat();
$changeFormat->changeImageToString();