Over a million developers have joined DZone.

Watermarks in our images with PHP and mod_rewrite

DZone's Guide to

Watermarks in our images with PHP and mod_rewrite

· Web Dev Zone
Free Resource

Learn how to build modern digital experience apps with Crafter CMS. Download this eBook now. Brought to you in partnership with Crafter Software

Imagine you have a set of images and you need to add watermark to all of them. You can do the work with an image editor (Gimp or Photoshop for example). It’s easy work, but if your image library is big, the easy work becomes hard. But imagine again you need to add a dynamic watermark, let’s say the current timestamp. To solve this problem we can use PHP’s GD image function set.

The idea is simple. Instead of opening the image directly, we are going to open a PHP script. This PHP script will open the original image file with imagecreatefromjpeg, add the footer and flush the new image to the browser with the properly headers.

I don’t want to rewrite all the anchor’s hrefs within my HTML files. Because of that, I’m going to use the same trick I used in my one of my posts. With a simple .htaccess in our jpg’s folder, our apache’s mod_rewrite will do all the work for us:

RewriteEngine on
RewriteRule !\.(php)$ watermark.php

And now our PHP script called watermark.php

$documentRoot = $_SERVER['DOCUMENT_ROOT'];
$filename = $documentRoot . $uri;
if (realpath(__FILE__) == realpath($filename)) {
$stringSize = 3;
$footerSize = ($stringSize==1) ? 12 : 15;
$footer = date('d/m/Y H:i:s');

list($width, $height, $image_type) = getimagesize($filename);
$im = imagecreatefromjpeg($filename);
imagefilledrectangle (
        $height - $footerSize, imagecolorallocate($im, 49, 49, 156));

        $width-(imagefontwidth($stringSize)*strlen($footer)) - 2,
        imagecolorallocate($im, 255, 255, 255));

header( 'Content-Type: image/png' );

Simple, isn’t it? You can change my blue footer with a your logo. Easy with PHP’s gd functions. Of course you need to have your PHP compiled with GD support.

Original image:

After transformation:

Crafter is a modern CMS platform for building modern websites and content-rich digital experiences. Download this eBook now. Brought to you in partnership with Crafter Software.


Published at DZone with permission of Gonzalo Ayuso, DZone MVB. See the original article here.

Opinions expressed by DZone contributors are their own.


Dev Resources & Solutions Straight to Your Inbox

Thanks for subscribing!

Awesome! Check your inbox to verify your email so you can start receiving the latest in tech news and resources.


{{ parent.title || parent.header.title}}

{{ parent.tldr }}

{{ parent.urlSource.name }}