做了个图片站，本身就是采的别人无水印的，但是怕别人来采我的，故加了水印，可担心以后换水印麻烦，原以搞了个输出里加上水印，原图不做更改的方法。本身也是从网上找到的一个小技术，这里把代码记录一下。

首先用这个要支持伪静态，在图片目录下放一个.HTACCESS文件

AddHandler watermarked .jpg
AddHandler watermarked .jpeg
AddHandler watermarked .gif
AddHandler watermarked .png
Action watermarked /imagesafe/imagesafe.php

然后使用下面的函数

<?php
$watermark = "watermark.png";
$image = $_SERVER["PATH_TRANSLATED"];
if (empty($image)) die();
if (!file_exists($image)) {
   header("404 Not Found");
   echo "File Not Found."; die();
}
$outputType = getFileType($image);
watermark($image, $watermark, $outputType);
function watermark($source, $watermark, $outputType="") {
   $sourceType = getFileType($source);
   $watermarkType = getFileType($watermark);
   if (empty($outputType)) $outputType = $sourceType;
   if ($outputType == "gif") $outputType = "png";
   header("Content-type:image/$outputType");
   $fileName = basename($source);
   preg_match_all("/(\.)/", $fileName, $dots);
   $dots = $dots[1];
   if (count($dots) > 1 || (strpos("$source","attach/thumb"))) {
      $fp = fopen($source, "rb");
      $contents = fread($fp, filesize($source));
      fclose($fp);
      echo $contents;
   }
   else {
      $createSource = "ImageCreateFrom".strtoupper($sourceType);
      $showImage = "Image".strtoupper($outputType);
      $createWatermark = "ImageCreateFrom".strtoupper($watermarkType);
      $output = $createSource($source);
      $logo = $createWatermark($watermark);
      ImageAlphaBlending($output, true);
      $x = ImageSX($output) - ImageSX($logo);
      $y = ImageSY($output) - ImageSY($logo);
      ImageCopy($output, $logo, $x, $y, 0, 0, ImageSX($logo), ImageSY($logo));
      $showImage($output);
      ImageDestroy($output);
      ImageDestroy($logo);
   }
}
function getFileType($string) {
   $type = strtolower(eregi_replace("^(.*)\.","",$string));
   if ($type == "jpg") $type = "jpeg";
   return $type;
}
?>

懂代码的看看吧，不懂代码的就略过吧！其它改改其中的路径就可以直接用了。