注意视频里写的两个info:
函数里的$info和$this->info是不同的变量

<?php

class Image{

private $image;

private $info;

public function __construct($src)

{

$info2 = getimagesize($src);

$this->info = array(

'width' => $info2[0],

'height' => $info2[1],

'type' => image_type_to_extension($info2['2'],false),

'mime' => $info2['mime']

);

$fun = "imagecreatefrom{$this->info['type']}";

$this->image = $fun($src);

}

public function thumb($width,$height)

{

$image_thumb = imagecreatetruecolor($width, $height);

imagecopyresampled($image_thumb, $this->image, 0, 0, 0, 0, $width, $height, $this->info['width'],$this->info['height']);

imagedestroy($this->image);

$this->image = $image_thumb;

}

public function show()

{

header("Content-type:".$this->info['mime']);

$funs = "image{$this->info['type']}";

$funs($this->image);

}

public function save($newimage)

{

$funs = "image{$this->info['type']}";

$funs($this->image,$newname.'.'.$this->info['type']);

}

public function __destruct()

{

imagedestroy($this->image);

}

}

?>

<title>给图片添加图片水印</title>

<?php

/*一、打开图片*/

$src = "001.png";

$info = getimagesize($src);

$type = image_type_to_extension($info[2],false);

$fun = "imagecreatefrom{$type}";

$image = $fun($src);

/*二、操作图片*/

$image_Mark = "logo.png";

$info2 = getimagesize($image_Mark);

$type2 = image_type_to_extension($info[2],false);

$fun2 = "imagecreatefrom{$type2}";

$water = $fun2($image_Mark);

//合并图片  0,0，$info[0],$info[1]将水印图片从原图的左上角顶点开始复制，0，0代表有多高复制多高，有多宽复制多宽。

imagecopymerge($image,$water,20,30,0,0,$info2[0],$info2[1],30);

imagedestroy($water);

/*三、输出图片*/

ob_clean();

header("content-type:".$info['mime']);

$funs = "image{$type}";

$funs($image);

$funs($image,"hi.".$type);  //保存图片

/*四、销毁图片*/

imagedestroy($image);

?>

teat.php

<?php 
    require "image_class.php";
    $src = '1.jpg';
    $image = new Image($src);
    $image->thumb(300,200);
    $image->show();

我的经过测试没有问题（代码如下）：

<?php 
//封装成类-压缩图片
class Image{	
    private $image;
    private $info;	
    //1.打开一张图片，读取到内存中	
    public function __construct($src){		
        $info = getimagesize($src);//获取图片信息放在$info里		
        $this->info = array(			
        'width' => $info[0],			
        'height' => $info[1],			
        'type' => image_type_to_extension($info[2],false),			
        'mime' => $info['mime']);		
        $fun = "imagecreatefrom{$this->info['type']}";		
        $this->image = $fun($src);	}	
        //2.操作图片(压缩)	
        public function thumb($width,$height){		
            $image_thumb = imagecreatetruecolor($width,$height);		
            imagecopyresampled($image_thumb,$this->image,0,0,0,0,$width,$height,$this->info['width'],$this->info['height']);		
            imagedestroy($this->image);		
            $this->image = $image_thumb;	
        }	
        //3.在浏览器中输出图片	
        public function show(){		
            header("Content-type:".$this->info['mime']);		
            $funs = "image{$this->info['type']}";		
            $funs($this->image);	
        }	
        //4.把图片保存到硬盘里	
        public function save($newname){		
            $funs = "image{$this->info['type']}";		
            $funs($this->image,$newname.'.'.$this->info['type']);	
        }	//5.销毁图片	
        public function __destruct(){		
                imagedestroy($this->image);	
        }
     }