The goal here is to watermark all images in a certain directory, except for thumbnails or other selection. You can either do this on each file prior to placing on your webserver - which is probably wise for CPU load issues - but let’s just say you want to do this for all files served in a single directory dynamically, a gallery for example.
The first step is to create a .png file with transparency which holds your watermark image. For this exercise, I’ve created this image:
(I’ve added the border to stand the image out from the background of the page).
Here is the original image we are going to test with:
After we have our watermark and sample image, we need to write a php file to use PHP’s GD function to apply this image to our original image. The particular function we use is imagecopy(). Here is the code I am using, I name it w.php:
<?php
$basedir="/home/user/public_html/com/gallery/";
$watermarkimage="tbwm.png";
$file=basename($_GET['i']);
$image = $basedir."/".$file;
$watermark = $basedir."/".$watermarkimage;
$im = imagecreatefrompng($watermark);
$ext = substr($image, -3);
if (strtolower($ext) == "gif") {
if (!$im2 = imagecreatefromgif($image)) {
echo "Error opening $image!"; exit;
}
} else if(strtolower($ext) == "jpg") {
if (!$im2 = imagecreatefromjpeg($image)) {
echo "Error opening $image!"; exit;
}
} else if(strtolower($ext) == "png") {
if (!$im2 = imagecreatefrompng($image)) {
echo "Error opening $image!"; exit;
}
} else {
die;
}
imagefilledrectangle($im2, 0 , (imagesy($im2))-(imagesy($im)) , imagesx($im2) , imagesy($im2) , imagecolorallocatealpha($im2, 0, 0, 0, 100) );
imagecopy($im2, $im, (imagesx($im2)-(imagesx($im))), (imagesy($im2))-(imagesy($im)), 0, 0, imagesx($im), imagesy($im));
$last_modified = gmdate('D, d M Y H:i:s T', filemtime ($image));
header("Last-Modified: $last_modified");
header("Content-Type: image/jpeg");
imagejpeg($im2,NULL,95);
imagedestroy($im);
imagedestroy($im2);
?>
This file is placed in the images directory.
Also in the images, create an .htaccess file with the following code:
RewriteEngine on
RewriteRule ^([^thumb].*\.[jJ].*)$ /com/gallery/w.php?i=$1
This tells the web server that instead of serving jpg files out of this directory, that we should instead process the filename with w.php and then serve to the browser. It also adds in a clause that if it starts with thumb_, that it will not run on this file. This is so it does not run on thumbnails.
Here is the resulting image, with watermark! This is served right out of an image directory with no watermark on the original picture:
