include 'phpqrcode/qrlib.php';  
value = 'http://enjointhing.cn'; //二维码内容errorCorrectionLevel = 'L';//容错级别 
matrixPointSize = 6;//生成图片大小 

//生成二维码图片 
QRcode::png(value, 'qrcode.png', errorCorrectionLevel,matrixPointSize, 2); 
logo = 'logo.png';//准备好的logo图片QR = 'qrcode.png';//已经生成的原始二维码图 

if (logo !== FALSE) {QR = imagecreatefromstring(file_get_contents(QR));logo = imagecreatefromstring(file_get_contents(logo));QR_width = imagesx(QR);//二维码图片宽度QR_height = imagesy(QR);//二维码图片高度logo_width = imagesx(logo);//logo图片宽度logo_height = imagesy(logo);//logo图片高度logo_qr_width = QR_width / 5;scale = logo_width/logo_qr_width; 
    logo_qr_height =logo_height/scale;from_width = (QR_width -logo_qr_width) / 2; 
    //重新组合图片并调整大小 
    imagecopyresampled(QR,logo, from_width,from_width, 0, 0, logo_qr_width,logo_qr_height, logo_width,logo_height); 
} 

//输出图片 
imagepng($QR, 'helloweba.png'); 
echo '<img src="helloweba.png">';