Automatically adding watermark on image download

问题

Is it possible to add a watermark when someone downloads an image from your website? If yes, what's the best way to do it?

Thanks in advance.

回答1:

If you mean when Right Click -> Saveing it, thats not possible I'm afraid.
If you generally mean that you have a dedicated download button or link, You could make It would redirect the request through a PHP file that will add the needed watermark and generate a new image file for download.

回答2:

I would suggest using a function imagecopymerge() to ad watermarks in php http://www.php.net/manual/en/function.imagecopymerge.php but as mentioned: they should be added before loading them in the browser. When user downloads them (right-click) then they're already served to their browser (and are usually in cache).

Ofcourse you could serve all images dynamically and check the http_referer on image load. And if that's missing or not an expected one (file isn't being loaded from your webpage) then add a water-mark but that's not foolproof.

回答3:

Please check following url same in this site , this ll help you lot

http://www.phpjabbers.com/put-watermark-on-images-using-php-php20.html

Following are from the above link

 <?php
function watermarkImage ($SourceFile, $WaterMarkText, $DestinationFile) { 
   list($width, $height) = getimagesize($SourceFile);
   $image_p = imagecreatetruecolor($width, $height);
   $image = imagecreatefromjpeg($SourceFile);
   imagecopyresampled($image_p, $image, 0, 0, 0, 0, $width, $height, $width, $height); 
   $black = imagecolorallocate($image_p, 0, 0, 0);
   $font = 'arial.ttf';
   $font_size = 10; 
   imagettftext($image_p, $font_size, 0, 10, 20, $black, $font, $WaterMarkText);
   if ($DestinationFile<>'') {
      imagejpeg ($image_p, $DestinationFile, 100); 
   } else {
      header('Content-Type: image/jpeg');
      imagejpeg($image_p, null, 100);
   };
   imagedestroy($image); 
   imagedestroy($image_p); 
};
?>
<?php
$SourceFile = 'image1.jpg';//image path
$DestinationFile = 'images/image1-watermark.jpg'; //Out put path
$WaterMarkText = 'Copyright Watermark text';
watermarkImage ($SourceFile, $WaterMarkText, $DestinationFile);
?>

回答4:

I have a better idea.

Since you said you wanna protect stuff when people Right Click and Select Save As. So, we can use the way how 9gag does.

Create an image with a fixed size of footer. Use a negative margin parent of the size of the footer of the bottom margin. Give overflow: hidden; so that the users cannot see the watermark, which is hidden from the view. Now when the users right click and save as image, they will have the watermark. Altogether, there is no place where the image is without watermark. So, while uploading the image, use the above said techniques to add the watermark.

Or, if you would like to make separate watermarked images, then you can check the hotlinked files and then serve watermarked images.

header("content-type: image/jpeg");
if (!isset($_SERVER['HTTP_REFERER'])){die("alert('Restricted Access!');");};
$_u=parse_url($_SERVER['HTTP_REFERER']);
$_u=preg_replace("/(www.)/i","",strtolower($_u['host']));
$_i=$_SERVER['HTTP_HOST'];
$_i=preg_replace("/(www.)/i","",strtolower($_i));
if ($_u != $_i){
   //handle this with gd or redirect
}

Follow the instructions in this tutorial to make the watermark on the picture.

来源：https://stackoverflow.com/questions/13377389/automatically-adding-watermark-on-image-download

标签

php

javascript

image-manipulation

watermark