Image watermark with PHP

To prevent quality images being stolen, we can use PHP to watermark web-images in popular formats like GIF/PNG/JPEG. We print a transparent gif-image on a jpeg-photo in this tutorial. For best results I prefer gif than png, because some png formats require extra functions to print a transparent image. We can convert this script to a batch-watermarker easily to watermark photo albums/galleries with multiple pictures by putting code in a loop or create a function.

Steps:

1. Load both images
2. Get size of both images
3. Copy watermark to main image
4. Print image to screen

PHP functions:
imagecreatefromgif
imagecreatefromjpeg
getimagesize
imagecopymerge
header
imagejpeg
imagedestroy

Watermark image:

Main image:

PHP Code:

<?php  

$main_img 		= "Porsche_911_996_Carrera_4S.jpg"; // main big photo / picture
$watermark_img	= "watermark.gif"; // use GIF or PNG, JPEG has no tranparency support
$padding 		= 3; // distance to border in pixels for watermark image
$opacity		= 100;	// image opacity for transparent watermark

$watermark 	= imagecreatefromgif($watermark_img); // create watermark
$image 		= imagecreatefromjpeg($main_img); // create main graphic

if(!$image || !$watermark) die("Error: main image or watermark could not be loaded!");


$watermark_size 	= getimagesize($watermark_img);
$watermark_width 	= $watermark_size[0];  
$watermark_height 	= $watermark_size[1];  

$image_size 	= getimagesize($main_img);  
$dest_x 		= $image_size[0] - $watermark_width - $padding;  
$dest_y 		= $image_size[1] - $watermark_height - $padding;


// copy watermark on main image
imagecopymerge($image, $watermark, $dest_x, $dest_y, 0, 0, $watermark_width, $watermark_height, $opacity);


// print image to screen
header("content-type: image/jpeg");   
imagejpeg($image);  
imagedestroy($image);  
imagedestroy($watermark);  

Example images:

Watermarked image with 10% opacity

Watermarked image with 50% opacity

Watermarked image with 100% opacity