这个是输出4个验证码的例子，对于汉字，需要font文件和imagettftext函数，用到的时候大家再网上搜索吧。

实例22 图片验证的核心代码

 
<?php 
//header("content-type:image/png"); 
$num ='1234'; 
$imagewidth=60; 
$imageheight=18; 

$numimage = imagecreate($imagewidth,$imageheight); 
imagecolorallocate($numimage,240,240,240); 
for($i=0;$i<strlen($num);$i++){ 
$x = mt_rand(1,8)+$imagewidth*$i/4; 
$y = mt_rand(1,$imageheight/4); 
$color=imagecolorallocate($numimage,mt_rand(0,150),mt_rand(0,150),mt_rand(0,150)); 
imagestring($numimage,5,$x,$y,$num[$i],$color); 
} 

for($i=0;$i<200;$i++){ 
$randcolor=imagecolorallocate($numimage,rand(200,255),rand(200,255),rand(200,255)); 
imagesetpixel($numimage,rand()%70,rand()%20,$randcolor); 
} 
imagepng($numimage); 
imagedestroy($numimage); 
?> 

这个是输出4个验证码的例子，对于汉字，需要font文件和imagettftext函数，用到的时候大家再网上搜索吧。你要产生随机数，那有mt_rand函数；你还要用到session保存这个随机数；如果需要转成utf-8，需要iconv函数。

实例23 缩略图

 
<?php 
class SimpleImage { 
var $image; 
var $image_type; 
function load($filename) { 
$image_info = getimagesize($filename); 
$this->image_type = $image_info[2]; 
if( $this->image_type == IMAGETYPE_JPEG ) { 
$this->image = imagecreatefromjpeg($filename); 
} elseif( $this->image_type == IMAGETYPE_GIF ) { 
$this->image = imagecreatefromgif($filename); 
} elseif( $this->image_type == IMAGETYPE_PNG ) { 
$this->image = imagecreatefrompng($filename); 
} 
} 
function save($filename, $image_type=IMAGETYPE_JPEG, $compression=75, $permissions=null) { 
if( $image_type == IMAGETYPE_JPEG ) { 
imagejpeg($this->image,$filename,$compression); 
} elseif( $image_type == IMAGETYPE_GIF ) { 
imagegif($this->image,$filename); 
} elseif( $image_type == IMAGETYPE_PNG ) { 
imagepng($this->image,$filename); 
} 
if( $permissions != null) { 
chmod($filename,$permissions); 
} 
} 
function output($image_type=IMAGETYPE_JPEG) { 
if( $image_type == IMAGETYPE_JPEG ) { 
imagejpeg($this->image); 
} elseif( $image_type == IMAGETYPE_GIF ) { 
imagegif($this->image); 
} elseif( $image_type == IMAGETYPE_PNG ) { 
imagepng($this->image); 
} 
} 
function getWidth() { 
return imagesx($this->image); 
} 
function getHeight() { 
return imagesy($this->image); 
} 
function resizeToHeight($height) { 
$ratio = $height / $this->getHeight(); 
$width = $this->getWidth() * $ratio; 
$this->resize($width,$height); 
} 
function resizeToWidth($width) { 
$ratio = $width / $this->getWidth(); 
$height = $this->getheight() * $ratio; 
$this->resize($width,$height); 
} 
function scale($scale) { 
$width = $this->getWidth() * $scale/100; 
$height = $this->getheight() * $scale/100; 
$this->resize($width,$height); 
} 
function resize($width,$height) { 
$new_image = imagecreatetruecolor($width, $height); 
imagecopyresampled($new_image, $this->image, 0, 0, 0, 0, $width, $height, $this->getWidth(), $this->getHeight()); 
$this->image = $new_image; 
} 
} 

$newfile = UPLOAD_DIR."/icons/".md5($_SESSION['USER']->email).".jpg";//上传文件保存的目录 
$image = new SimpleImage(); 
$image->load($_FILES['icons']['tmp_name']);//上传的临时文件名 
$image->resizeToWidth(80);设置宽度 
$image->save($newfile); 
?>