24 Apr 10 Watermark your images with PHP on the fly

By Peter Radics :: web design - cleanweb.hu
Tuesday 9 January 2007

Commands we will use:

header()
imagefrompng()
imagefromjpeg()
imagecopymerge()
imagejpeg()
imagedestroy()
getimagesize()

The method:

1. send your browser an image header, because you will create a new image:

header("content-type: image/jpeg");

2. get your watermark image, and the other image what your want to get watermarked too:

$wm = imagecreatefrompng("watermark.png");
$img = imagecreatefromjpeg("myimage.jpg");


4. if you want to center your watermark on your image, you should calculate it's position:

$wmsize = getimagesize("watermark.png");
$imgsize = getimagesize("myimage.jpg");
$destx = ($imgsize[0] - $wmsize[0]) / 2;
$desty = ($imgsize[1] - $wmsize[1]) / 2;


3.use the imagecopymerge() function to copy your watermark to your image:

imagecopymerge($img,$wm,$destx,$desty, 0, 0, $wmsize[0], $wmsize[1], 75);

- the last parameter of the above function is the alpha transparency

4. send the new image to the browser:

imagejpeg($img);


5. finally, destroy your sources:

imagedestroy($img);
imagejpeg($img);

The full source:

<?php

header("content-type: image/jpeg");

$wm = imagecreatefrompng("watermark.png");
$img = imagecreatefromjpeg("myimage.jpg");

$wmsize = getimagesize("watermark.png");
$imgsize = getimagesize("myimage.jpg");
$destx = ($imgsize[0] - $wmsize[0]) / 2;
$desty = ($imgsize[1] - $wmsize[1] / 2;

imagecopymerge($img,$wm,$destx,$desty, 0, 0, $wmsize[0], $wmsize[1], 75);

imagejpeg($img);

imagedestroy($img);
imagedestroy($wm);
?>

By Peter Radics :: web design - cleanweb.hu

About the Author

web designer, programmer