Add Watermark to a Image with PHP GD

Sometimes we need to add watermark to our image contents. There are several ways to add watermark on image. Like editing image with Photoshop or other application and add watermark. This process is ok but not enough for a large dynamic website. Today I am going to show you how you can add watermark to images automatically with PHP GD functions.


Watermark Function:

function watermark($img, $watermark){
	// Set content type
	header('Content-type: image/jpg');
	// Cerate watermark
	$wm = imagecreatefrompng($watermark);
	// getting dimensions of watermark image
	$wm_size = getimagesize($watermark);
	// Create image
	$image = imagecreatefromjpeg($img);
	// Get image size
	$size = getimagesize($img);
	// placing the watermark 10px from bottom and right
	$dest_x = $size[0] - $wm_size[0] - 10;  
	$dest_y = $size[1] - $wm_size[1] - 10;
	// blending the images together
	imagealphablending($image, true);
	imagealphablending($wm, true); 
	// creating the new image
	imagecopy($image, $wm, $dest_x, $dest_y, 0, 0, $wm_size[0] , $wm_size[1]);
	// Send image to the browser 
	imagejpeg($image, null, 100);
	//Save image in cache
	// destroy image and watermak
	imagedestroy($image);
	imagedestroy($wm);
}

Usage:

watermark('image.jpg', 'watermark.png');