PHP function to add watermark on an image

How to apply watermark on a image? Watermarking means applying an image with a transparent/non transparent background on another image to protect the image from unauthorised use of it by other parties which doesn;t own the image. The following function can be used to add watermark on images.
	The function accepts 2 parameters 1. the source image - the image on which watermark has to be applied 2. the position of the watermark image on the source image.
*****************CODE START*************** <?php function apply_watermark($imagesource, $position = 'bottomright'){ $info = getimagesize($imagesource); if($info){ switch($info[2]){ case 1 : { $image = imagecreatefromgif($imagesource); break;}//gif case 2 : { $image = imagecreatefromjpeg($imagesource); break; }//jpg case 3 : { $image = imagecreatefrompng($imagesource); break; }//png default : { exit("Unsupporter file type"); } } } else{ print "Can't read required image data"; } //watermark image $watermark = @imagecreatefrompng(getenv('DOCUMENT_ROOT').'/images/logo.png'); $imagewidth = imagesx($image); $imageheight = imagesy($image); $watermarkwidth = imagesx($watermark); $watermarkheight = imagesy($watermark); switch($position){ case 'topleft': $startwidth = 0; $startheight = 0; break; case 'topright': $startwidth = ($imagewidth - $watermarkwidth); $startheight = 0; break; case 'middle': $startwidth = (($imagewidth - $watermarkwidth)/2); $startheight = (($imageheight - $watermarkheight)/2); break; case 'bottomleft': $startwidth = 0; $startheight = ($imageheight - $watermarkheight); break; case 'bottomright': default: $startwidth = ($imagewidth - $watermarkwidth); $startheight = ($imageheight - $watermarkheight); break; } imagecopy($image, $watermark, $startwidth, $startheight, 0, 0, $watermarkwidth, $watermarkheight); // Output final image switch($info[2]){ case 1 : { imagegif($image, $imagesource, 100); break;}//gif case 2 : { imagejpeg($image, $imagesource, 100); break; }//jpg case 3 : { imagepng($image, $imagesource, 100); break; }//png default : { exit("Unsupporter file type"); break;} } imagedestroy($watermark); } ?> *****************CODE END***************