Quivertree publications are an image library website and like most image library websites, they wanted their images watermarked

There are a lot of scripts floating about for adding watermarks to image as they are served up to the end user, but a lot of these made it too easy for the end user to ascertain the location of the original, ‘un-watermarked’ image, and as there was already a backend process involved in loading the images and their meta-data, it made sense to write code that generated the final watermarked image in advance. I used this fantastic tutorial on Watermarking Images on the Fly in PHP as a starting point and came up with this:

$dir = dirList ('temp_images');//function that returns a list of all images in the temp_images directory - these images were already uploaded to this location by the site admin
if($dir)://if there are images in the temp_images directory, then away we go!
	foreach($dir as $key => $value): //for each image $key = image number, $value = the image name (e.g myImage.jpg)
		$imgsrc = 'temp_images/'.$value; //source image without watermark
		$imgout = 'temp_watermark/'.$value; //where to save the image with the watermark
		watermark_img($imgsrc,$imgout);//this function is below
	endforeach;
else:
	echo 'You need to upload some images first';
endif;

Here is the watermark_img function:

function watermark_img($imgsrc,$saveas) {
		$watermark = imagecreatefrompng('images/watermark.png');  //location of my watermark
		$watermark_width = imagesx($watermark);
		$watermark_height = imagesy($watermark);
		$image = imagecreatetruecolor($watermark_width, $watermark_height);
		$image = imagecreatefromjpeg($imgsrc);
		$size = getimagesize($imgsrc);
		$mainimg_w_pos = $size[0] / 2; //get half of the main image
		$watermark_w_pos = $watermark_width / 2; //get half of the watermark
		$dest_x = $mainimg_w_pos - $watermark_w_pos; //watermark sits at half of width minus half its own width
		$mainimg_h_pos = $size[1] / 2; //get half of the main image
		$watermark_h_pos = $watermark_height / 2; //get half of the watermark
		$dest_y = $mainimg_h_pos - $watermark_h_pos; //watermark sits at half of width minus half its own width
		_ckdir($saveas);//function to test that save as location is available
		imagecopymerge($image, $watermark, $dest_x, $dest_y, 0, 0, $watermark_width, $watermark_height, 100);
		imagejpeg($image,$saveas,100);
	}