Add 'Watermark' to images with php

Question

I have a website where users may upload images...

I need to add my logo (watermark) to the images once they are uploaded.

How can I do so?

And it is important that the watermark is in a corner where it will be visible, for example I have seen websites which generates a watermark on the fly, and puts the mark wherever the background of the main image is "the same color" so the watermark sticks out if you know what I mean.

Anybody have a good tutorial or article about this? Or know of any function in php which I would need to find the position of the watermark?

Answer 1

A good example in the PHP manual:

// Load the stamp and the photo to apply the watermark to
$stamp = imagecreatefrompng('stamp.png');
$im = imagecreatefromjpeg('photo.jpeg');

// Set the margins for the stamp and get the height/width of the stamp image
$marge_right = 10;
$marge_bottom = 10;
$sx = imagesx($stamp);
$sy = imagesy($stamp);

// Copy the stamp image onto our photo using the margin offsets and the photo 
// width to calculate positioning of the stamp. 
imagecopy($im, $stamp, imagesx($im) - $sx - $marge_right, imagesy($im) - $sy - $marge_bottom, 0, 0, imagesx($stamp), imagesy($stamp));

// Output and free memory
header('Content-type: image/png');
imagepng($im);
imagedestroy($im);