php支持imagemagick与gd库缩略图生成类

分享一个php实现的缩略图类，支持imagemagick及gd库两种处理的缩略图生成类，功能包括按区域裁剪图片、添加水印、包括水印功能、透明度等，需要的朋友参考下。

php实现同时支持imagemagick及gd库的缩略图生成类与用法。

一、功能: 1、按比例缩小/放大 2、填充背景色 3、按区域裁剪 4、添加水印，包括水印的位置，透明度等 使用imagemagick/GD库实现，imagemagick地址：www.imagemagick.org

先安装imagemagick，安装方法： http://bbs.it-home.org/php/25871.html

二、实现方法： 1，PicThumb.class.php类文件：

<?php 
/** 缩略图生成类,支持imagemagick及gd库两种处理 
*  Date:  2013-07-15 
*  Author: fdipzone 
*  Ver:  1.2 
* 
*  Func: 
*  public set_config: 设置参数 
*  public create_thumb: 生成缩略图 
*  private fit: 缩略图片 
*  private crop: 裁剪图片 
*  private gd_fit: GD库缩略图片 
*  private gd_crop: GD库裁剪图片 
*  private get_size: 获取要转换的size 
*  private get_crop_offset: 获取裁图的偏移量 
*  private add_watermark: 添加水印 
*  private check_handler: 判断处理程序是否已安装 
*  private create_dirs: 创建目录 
*  private exists: 判断参数是否存在 
*  private to_log: 记录log 
*  private hex2rgb: hex颜色转rgb颜色 
*  private get_file_ext: 获取图片类型 
* 
*  ver:  1.1 增加GD库处理 
*  ver:  1.2 增加width,height错误参数处理 
*        增加当图片colorspace不为RGB时作转RGB处理 
*        修正使用crop保存为gif时出现透明无效区域问题，使用+repage参数，删除透明无效区域即可 
* 
*  tips:建议使用imagemagick 
*    GD库不支持透明度水印,如果必须使用透明水印,请将水印图片做成有透明度。 
*    GD库输出gif如加透明水印，会有问题。 
*/
  
class PicThumb{ // class start 
  
  private $_log = null;      // log file 
  private $_handler = null;    // 进行图片处理的程序,imagemagick/gd库 
  private $_type = 'fit';     // fit or crop 
  private $_source = null;     // 原图路径 
  private $_dest = null;      // 缩略图路径 
  private $_watermark = null;   // 水印图片 
  private $_opacity = 75;     // 水印圖片透明度,gd库不支持 
  private $_gravity = 'SouthEast'; // 水印摆放位置 NorthWest, North, NorthEast, West, Center, East, SouthWest, South, SouthEast 
  private $_geometry = '+10+10';  // 水印定位,gd库不支持 
  private $_croppos = 'TL';    // 截图的位置 TL TM TR ML MM MR BL BM BR 
  private $_bgcolor = null;    // 填充的背景色 
  private $_quality = 90;     // 生成的图片质量 
  private $_width = null;     // 指定区域宽度 
  private $_height = null;     // 指定区域高度 
  
  // 初始化 
  public function __construct($logfile=''){ 
    if($logfile!=''){ 
      $this->_log = $logfile; 
    } 
  } 
  
  // 设置参数 
  public function set_config($param=array()){ 
    $this->_handler = $this->exists($param, 'handler')? strtolower($param['handler']) : null; 
    $this->_type = $this->exists($param, 'type')? strtolower($param['type']) : 'fit'; 
    $this->_watermark = $this->exists($param, 'watermark')? $param['watermark'] : null; 
    $this->_opacity = $this->exists($param, 'opacity')? $param['opacity'] : 75; 
    $this->_gravity = $this->exists($param, 'gravity')? $param['gravity'] : 'SouthEast'; 
    $this->_geometry = $this->exists($param, 'geometry')? $param['geometry'] : '+10+10'; 
    $this->_croppos = $this->exists($param, 'croppos')? $param['croppos'] : 'TL'; 
    $this->_bgcolor = $this->exists($param, 'bgcolor')? $param['bgcolor'] : null; 
    $this->_quality = $this->exists($param, 'quality')? $param['quality'] : 90; 
    $this->_width = $this->exists($param, 'width')? $param['width'] : null; 
    $this->_height = $this->exists($param, 'height')? $param['height'] : null; 
  } 
  
  /** 创建缩略图 
  * @param String $source 原图 
  * @param String $dest  目标图 
  * @return boolean 
  */
  public function create_thumb($source, $dest){ 
    // 检查使用的handler是否已安装 
    if(!$this->check_handler()){ 
      $this->to_log('handler not installed'); 
      return false; 
    } 
    // 判断区域宽高是否正确 
    if(!is_numeric($this->_width) || !is_numeric($this->_height) || $this->_width<=0 || $this->_height<=0){ 
      $this->to_log('width or height invalid'); 
      return false; 
    } 
  
    // 判断源文件是否存在 
    if(!file_exists($source)){ 
      $this->to_log($source.' not exists'); 
      return false; 
    } 
  
    // 创建目标文件路径 
    if(!$this->create_dirs($dest)){ 
      $this->to_log(dirname($dest).' create fail'); 
      return false; 
    } 
  
    $this->_source = $source;  // 源文件 
    $this->_dest = $dest;    // 目标文件 
  
    // 处理图片 
    switch($this->_type){ 
      case 'fit': 
        if($this->_handler=='imagemagick'){ 
          return $this->fit(); 
        }else{ 
          return $this->gd_fit(); 
        } 
        break; 
  
      case 'crop': 
        if($this->_handler=='imagemagick'){ 
          return $this->crop(); 
        }else{ 
          return $this->gd_crop(); 
        } 
        break; 
  
      default: 
        $this->to_log($this->_type.' not fit and crop'); 
        return false; 
    } 
  } 
  
  /** 按比例压缩或拉伸图片 
  * @return boolean 
  */
  private function fit(){ 
  
    // 判断是否填充背景 
    $bgcolor = ($this->_bgcolor!=null)?  
    sprintf(" -background '%s' -gravity center -extent '%sx%s' ", $this->_bgcolor, $this->_width, $this->_height) : ""; 
  
    // 判断是否要转为RGB 
    $source_info = getimagesize($this->_source); 
    $colorspace = (!isset($source_info['channels']) || $source_info['channels']!=3)? ' -colorspace RGB ' : ''; 
  
    // 命令行 
    $cmd = sprintf("convert -resize '%sx%s' '%s' %s -quality %s %s '%s'", $this->_width, $this->_height, $this->_source, $bgcolor, 
$this->_quality, $colorspace, $this->_dest); 
  
    // 记录执行的命令 
    $this->to_log($cmd); 
  
    // 执行命令 
    exec($cmd); 
  
    // 添加水印 
    $this->add_watermark($this->_dest); 
  
    return is_file($this->_dest)? true : false; 
  } 
  
  /** 裁剪图片 
  * @return boolean 
  */
  private function crop(){ 
    // 获取生成的图片尺寸 
    list($pic_w, $pic_h) = $this->get_size(); 
  
    // 获取截图的偏移量 
    list($offset_w, $offset_h) = $this->get_crop_offset($pic_w, $pic_h); 
  
    // 判断是否要转为RGB 
    $source_info = getimagesize($this->_source); 
    $colorspace = (!isset($source_info['channels']) || $source_info['channels']!=3)? ' -colorspace RGB ' : ''; 
  
    // 命令行 
    $cmd = sprintf("convert -resize '%sx%s' '%s' -quality %s %s -crop %sx%s+%s+%s +repage '%s'", $pic_w, $pic_h, $this->_source, 
$this->_quality, $colorspace, $this->_width, $this->_height, $offset_w, $offset_h, $this->_dest); 
  
    // 记录执行的命令 
    $this->to_log($cmd); 
  
    // 执行命令 
    exec($cmd); 
  
    // 添加水印 
    $this->add_watermark($this->_dest); 
  
    return is_file($this->_dest)? true : false; 
  } 
  
  /** GD库按比例压缩或拉伸图片 
  * @return boolean 
  */
  private function gd_fit(){ 
    // 获取生成的图片尺寸 
    list($pic_w, $pic_h) = $this->get_size(); 
  
    list($owidth, $oheight, $otype) = getimagesize($this->_source); 
  
    switch($otype){ 
      case 1: $source_img = imagecreatefromgif($this->_source); break; 
      case 2: $source_img = imagecreatefromjpeg($this->_source); break; 
      case 3: $source_img = imagecreatefrompng($this->_source); break; 
      default: return false; 
    } 
  
    // 按比例缩略/拉伸图片 
    $new_img = imagecreatetruecolor($pic_w, $pic_h); 
    imagecopyresampled($new_img, $source_img, 0, 0, 0, 0, $pic_w, $pic_h, $owidth, $oheight); 
  
    // 判断是否填充背景 
    if($this->_bgcolor!=null){ 
      $bg_img = imagecreatetruecolor($this->_width, $this->_height); 
      $rgb = $this->hex2rgb($this->_bgcolor); 
      $bgcolor =imagecolorallocate($bg_img, $rgb['r'], $rgb['g'], $rgb['b']); 
      imagefill($bg_img, 0, 0, $bgcolor); 
      imagecopy($bg_img, $new_img, (int)(($this->_width-$pic_w)/2), (int)(($this->_height-$pic_h)/2), 0, 0, $pic_w, $pic_h); 
      $new_img = $bg_img; 
    } 
  
    // 获取目标图片的类型 
    $dest_ext = $this->get_file_ext($this->_dest); 
  
    // 生成图片 
    switch($dest_ext){ 
      case 1: imagegif($new_img, $this->_dest, $this->_quality); break; 
      case 2: imagejpeg($new_img, $this->_dest, $this->_quality); break; 
      case 3: imagepng($new_img, $this->_dest, (int)(($this->_quality-1)/10)); break; 
    } 
  
    if(isset($source_img)){ 
      imagedestroy($source_img); 
    } 
  
    if(isset($new_img)){ 
      imagedestroy($new_img); 
    } 
  
    // 添加水印 
    $this->add_watermark($this->_dest); 
  
    return is_file($this->_dest)? true : false; 
  } 
  
  /** GD库裁剪图片 
  * @return boolean 
  */
  private function gd_crop(){ 
  
    // 获取生成的图片尺寸 
    list($pic_w, $pic_h) = $this->get_size(); 
  
    // 获取截图的偏移量 
    list($offset_w, $offset_h) = $this->get_crop_offset($pic_w, $pic_h); 
  
    list($owidth, $oheight, $otype) = getimagesize($this->_source); 
  
    switch($otype){ 
      case 1: $source_img = imagecreatefromgif($this->_source); break; 
      case 2: $source_img = imagecreatefromjpeg($this->_source); break; 
      case 3: $source_img = imagecreatefrompng($this->_source); break; 
      default: return false; 
    } 
  
    // 按比例缩略/拉伸图片 
    $tmp_img = imagecreatetruecolor($pic_w, $pic_h); 
    imagecopyresampled($tmp_img, $source_img, 0, 0, 0, 0, $pic_w, $pic_h, $owidth, $oheight); 
  
    // 裁剪图片 
    $new_img = imagecreatetruecolor($this->_width, $this->_height); 
    imagecopyresampled($new_img, $tmp_img, 0, 0, $offset_w, $offset_h, $this->_width, $this->_height, $this->_width, $this->_height); 
  
    // 获取目标图片的类型 
    $dest_ext = $this->get_file_ext($this->_dest); 
  
    // 生成图片 
    switch($dest_ext){ 
      case 1: imagegif($new_img, $this->_dest, $this->_quality); break; 
      case 2: imagejpeg($new_img, $this->_dest, $this->_quality); break; 
      case 3: imagepng($new_img, $this->_dest, (int)(($this->_quality-1)/10)); break; 
    } 
  
    if(isset($source_img)){ 
      imagedestroy($source_img); 
    } 
  
    if(isset($tmp_img)){ 
      imagedestroy($tmp_img); 
    } 
  
    if(isset($new_img)){ 
      imagedestroy($new_img); 
    } 
  
    // 添加水印 
    $this->add_watermark($this->_dest); 
  
    return is_file($this->_dest)? true : false; 
  } 
  
  /** 获取目标图生成的size 
  * @return Array $width, $height 
  */
  private function get_size(){ 
    list($owidth, $oheight) = getimagesize($this->_source); 
    $width = (int)($this->_width); 
    $height = (int)($this->_height); 
      
    switch($this->_type){ 
      case 'fit': 
        $pic_w = $width; 
        $pic_h = (int)($pic_w*$oheight/$owidth); 
        if($pic_h>$height){ 
          $pic_h = $height; 
          $pic_w = (int)($pic_h*$owidth/$oheight); 
        } 
        break; 
      case 'crop': 
        if($owidth>$oheight){ 
          $pic_h = $height; 
          $pic_w = (int)($pic_h*$owidth/$oheight); 
        }else{ 
          $pic_w = $width; 
          $pic_h = (int)($pic_w*$oheight/$owidth); 
        } 
        break; 
    } 
    return array($pic_w, $pic_h); 
  } 
  
  /** 获取截图的偏移量 
  * @param int $pic_w 图宽度 
  * @param int $pic_h 图高度 
  * @return Array $offset_w, $offset_h 
  */
  private function get_crop_offset($pic_w, $pic_h){ 
    $offset_w = 0; 
    $offset_h = 0; 
      
    switch(strtoupper($this->_croppos)){ 
      case 'TL': 
        $offset_w = 0; 
        $offset_h = 0; 
        break; 
  
      case 'TM': 
        $offset_w = (int)(($pic_w-$this->_width)/2); 
        $offset_h = 0; 
        break; 
  
      case 'TR': 
        $offset_w = (int)($pic_w-$this->_width); 
        $offset_h = 0; 
        break; 
  
      case 'ML': 
        $offset_w = 0; 
        $offset_h = (int)(($pic_h-$this->_height)/2); 
        break; 
  
      case 'MM': 
        $offset_w = (int)(($pic_w-$this->_width)/2); 
        $offset_h = (int)(($pic_h-$this->_height)/2); 
        break; 
  
      case 'MR': 
        $offset_w = (int)($pic_w-$this->_width); 
        $offset_h = (int)(($pic_h-$this->_height)/2); 
        break; 
  
      case 'BL': 
        $offset_w = 0; 
        $offset_h = (int)($pic_h-$this->_height); 
        break; 
  
      case 'BM': 
        $offset_w = (int)(($pic_w-$this->_width)/2); 
        $offset_h = (int)($pic_h-$this->_height); 
        break; 
  
      case 'BR': 
        $offset_w = (int)($pic_w-$this->_width); 
        $offset_h = (int)($pic_h-$this->_height); 
        break; 
    } 
    return array($offset_w, $offset_h); 
  } 
  
  /** 添加水印 
  * @param String $dest 图片路径 
  */
  private function add_watermark($dest){ 
    if($this->_watermark!=null && file_exists($this->_watermark) && file_exists($dest)){ 
      list($owidth, $oheight, $otype) = getimagesize($dest); 
      list($w, $h, $wtype) = getimagesize($this->_watermark); 
  
      // 水印图比原图要小才加水印 
      if($w<=$owidth && $h<=$oheight){ 
  
        if($this->_handler=='imagemagick'){ // imagemagick 添加水印 
  
          $cmd = sprintf("composite -gravity %s -geometry %s -dissolve %s '%s' %s %s", $this->_gravity, $this->_geometry, 
$this->_opacity, $this->_watermark, $dest, $dest); 
  
          $this->to_log($cmd); 
  
          exec($cmd); 
  
        }else{ // gd 添加水印 
  
          switch($wtype){ 
            case 1: $water_img = imagecreatefromgif($this->_watermark); break; 
            case 2: $water_img = imagecreatefromjpeg($this->_watermark); break; 
            case 3: $water_img = imagecreatefrompng($this->_watermark); break; 
            default: return false; 
          } 
  
          switch($otype){ 
            case 1: $dest_img = imagecreatefromgif($dest); break; 
            case 2: $dest_img = imagecreatefromjpeg($dest); break; 
            case 3: $dest_img = imagecreatefrompng($dest); break; 
            default: return false; 
          } 
  
          // 水印位置 
          switch(strtolower($this->_gravity)){ 
            case 'northwest': 
              $posX = 0; 
              $posY = 0; 
              break; 
            case 'north': 
              $posX = ($owidth - $w) / 2; 
              $posY = 0; 
              break; 
            case 'northeast': 
              $posX = $owidth - $w; 
              $posY = 0; 
              break; 
            case 'west': 
              $posX = 0; 
              $posY = ($oheight - $h) / 2; 
              break; 
            case 'center': 
              $posX = ($owidth - $w) / 2; 
              $posY = ($oheight - $h) / 2; 
              break; 
            case 'east': 
              $posX = $owidth - $w; 
              $posY = ($oheight - $h) / 2; 
              break; 
            case 'southwest': 
              $posX = 0; 
              $posY = $oheight - $h; 
              break; 
            case 'south': 
              $posX = ($owidth - $w) / 2; 
              $posY = $oheight - $h; 
              break; 
            case 'southeast': 
              $posX = $owidth - $w; 
              $posY = $oheight - $h; 
              break; 
          } 
  
          imagealphablending($dest_img, true); 
          imagecopy($dest_img, $water_img, $posX, $posY, 0, 0, $w, $h); 
  
          switch($otype){ 
            case 1:imagegif($dest_img, $dest, $this->_quality); break; 
            case 2:imagejpeg($dest_img, $dest, $this->_quality); break; 
            case 3:imagepng($dest_img, $dest, (int)(($this->_quality-1)/10)); break; 
          } 
  
          if(isset($water_img)){ 
            imagedestroy($water_img); 
          } 
  
          if(isset($dest_img)){ 
            imagedestroy($dest_img); 
          } 
        } 
      } 
    } 
  } 
  
  /** 判断处理程序是否已安装 
  * @return boolean 
  */
  private function check_handler(){ 
  
    $handler = $this->_handler; 
  
    if(!in_array($handler, array('imagemagick', 'gd', null))){ 
      return false; 
    } 
  
    // 检查是否有安装imagemagick 
    $imagemagick_installed = strstr(shell_exec('convert -version'),'Version: ImageMagick')!=''? true : false; 
  
    // 检查是否有安装gd库 
    $gd_installed = function_exists('gd_info')? true : false; 
  
    switch($handler){ 
      case 'imagemagick': 
        return $imagemagick_installed; 
        break; 
  
      case 'gd': 
        return $gd_installed; 
        break; 
  
      case null: 
        if($imagemagick_installed){ 
          $this->_handler = 'imagemagick'; 
          return true; 
        } 
  
        if($gd_installed){ 
          $this->_handler = 'gd'; 
          return true; 
        } 
        break; 
    } 
    return false; 
  } 
  
  /** 创建图片目录 
  * @param String $path 
  * @return boolean 
  */
  private function create_dirs($dest){ 
    if(!is_dir(dirname($dest))){ 
      return mkdir(dirname($dest), 0777, true); 
    } 
    return true; 
  } 
  
  /** 判断参数是否存在 
  * @param Array  $obj 数组对象 
  * @param String $key 要查找的key 
  * @return boolean 
  */
  private function exists($obj,$key=''){ 
    if($key==''){ 
      return isset($obj) && !empty($obj); 
    }else{ 
      $keys = explode('.',$key); 
      for($i=0,$max=count($keys); $i<$max; $i++){ 
        if(isset($obj[$keys[$i]])){ 
          $obj = $obj[$keys[$i]]; 
        }else{ 
          return false; 
        } 
      } 
      return isset($obj) && !empty($obj); 
    } 
  } 
  
  /** 记录log 
  * @param String $msg 要记录的log讯息 
  */
  private function to_log($msg){ 
    if($this->_log){ 
      $msg = '['.date('Y-m-d H:i:s').']'.$msg."\r\n"; 
      file_put_contents($this->_log, $msg, FILE_APPEND); 
    } 
  } 
  
  /** hex颜色转rgb颜色 
  * @param String $color hex颜色 
  * @return Array 
  */
  private function hex2rgb($hexcolor){ 
    $color = str_replace('#', '', $hexcolor); 
    if (strlen($color) > 3) { 
      $rgb = array( 
        'r' => hexdec(substr($color, 0, 2)), 
        'g' => hexdec(substr($color, 2, 2)), 
        'b' => hexdec(substr($color, 4, 2)) 
      ); 
    } else { 
      $r = substr($color, 0, 1) . substr($color, 0, 1); 
      $g = substr($color, 1, 1) . substr($color, 1, 1); 
      $b = substr($color, 2, 1) . substr($color, 2, 1); 
      $rgb = array( 
        'r' => hexdec($r), 
        'g' => hexdec($g), 
        'b' => hexdec($b) 
      ); 
    } 
    return $rgb; 
  } 
  
  /** 获取图片类型 
  * @param String $file 图片路径 
  * @return int 
  */
  private function get_file_ext($file){ 
    $filename = basename($file); 
    list($name, $ext)= explode('.', $filename); 
  
    $ext_type = 0; 
  
    switch(strtolower($ext)){ 
      case 'jpg': 
      case 'jpeg': 
        $ext_type = 2; 
        break; 
      case 'gif': 
        $ext_type = 1; 
        break; 
      case 'png': 
        $ext_type = 3; 
        break; 
    } 
    return $ext_type; 
  } 
  
} // class end 
?>

2，php缩略图类的调用示例。

<?php 
define('ROOT', dirname(__FILE__)); 
  
require(ROOT."/PicThumb.class.php"); 
  
$logfile = ROOT.'/PicThumb.log'; 
$source1 = ROOT.'/pic/source.jpg'; 
$dest1 = ROOT.'/pic/1.jpg'; 
$dest2 = ROOT.'/pic/2.gif'; 
$dest3 = ROOT.'/pic/3.png'; 
  
$source2 = ROOT.'/pic/source_cmyk.jpg'; 
$dest4 = ROOT.'/pic/4.jpg'; 
$dest5 = ROOT.'/pic/5.gif'; 
$dest6 = ROOT.'/pic/6.png'; 
  
$watermark = ROOT.'/pic/watermark.png'; 
  
// 按比例生成缩略图 
$param = array( 
  'type' => 'fit', 
  'width' => 100, 
  'height' => 100, 
); 
  
$obj = new PicThumb($logfile); 
$obj->set_config($param); 
$flag = $obj->create_thumb($source1, $dest1); 
  
if($flag){ 
  echo '<img  src="pic/'.basename($dest1).'" alt="php支持imagemagick与gd库缩略图生成类 " >'; 
}else{ 
  echo 'create thumb fail'; 
} 
  
// 按比例生成缩略图,不足部分用#FF0000填充 
$param = array( 
  'type' => 'fit', 
  'width' => 100, 
  'height' => 100, 
  'bgcolor' => '#FFFF00'
); 
  
$obj = new PicThumb($logfile); 
$obj->set_config($param); 
$flag = $obj->create_thumb($source1, $dest2); 
  
if($flag){ 
  echo '<img  src="pic/'.basename($dest2).'" alt="php支持imagemagick与gd库缩略图生成类 " >'; 
}else{ 
  echo 'create thumb fail'; 
} 
  
// 裁剪250x250的缩略图,裁剪位置是底部中间,水印位置西南,透明度50 
$param = array( 
  'type' => 'crop', 
  'croppos' => 'BM', 
  'width' => 250, 
  'height' => 250, 
  'watermark' => $watermark, 
  'opacity' => 50, 
  'gravity' => 'SouthWest'
); 
  
$obj = new PicThumb($logfile); 
$obj->set_config($param); 
$flag = $obj->create_thumb($source1, $dest3); 
  
if($flag){ 
  echo '<img  src="pic/'.basename($dest3).'" alt="php支持imagemagick与gd库缩略图生成类 " >'; 
}else{ 
  echo 'create thumb fail'; 
} 
  
// 按比例生成缩略图 CMYK格式 
$param = array( 
  'type' => 'fit', 
  'width' => 100, 
  'height' => 100, 
); 
  
$obj = new PicThumb($logfile); 
$obj->set_config($param); 
$flag = $obj->create_thumb($source2, $dest4); 
  
if($flag){ 
  echo '<img  src="pic/'.basename($dest4).'" alt="php支持imagemagick与gd库缩略图生成类 " >'; 
}else{ 
  echo 'create thumb fail'; 
} 
  
// 按比例生成缩略图,不足部分用#FF0000填充 CMYK格式 
$param = array( 
  'type' => 'fit', 
  'width' => 100, 
  'height' => 100, 
  'bgcolor' => '#FFFF00'
); 
  
$obj = new PicThumb($logfile); 
$obj->set_config($param); 
$flag = $obj->create_thumb($source2, $dest5); 
  
if($flag){ 
  echo '<img  src="pic/'.basename($dest5).'" alt="php支持imagemagick与gd库缩略图生成类 " >'; 
}else{ 
  echo 'create thumb fail'; 
} 
  
// 裁剪250x250的缩略图,裁剪位置是底部中间,水印位置西南,透明度50 CMYK格式 
$param = array( 
  'type' => 'crop', 
  'croppos' => 'BM', 
  'width' => 250, 
  'height' => 250, 
  'watermark' => $watermark, 
  'opacity' => 50, 
  'gravity' => 'SouthWest'
); 
  
$obj = new PicThumb($logfile); 
$obj->set_config($param); 
$flag = $obj->create_thumb($source2, $dest6); 
  
if($flag){ 
  echo '<img  src="pic/'.basename($dest6).'" alt="php支持imagemagick与gd库缩略图生成类 " >'; 
}else{ 
  echo 'create thumb fail'; 
} 
?>