PHP watermarking

Question

i am using this code to create watermark.

    $image = \'1.jpg\';
    $overlay = \'stamp.png\';
    $opacity = \"20\";
    if (!file_exists($image)) {
               


        

Answer 1

The jpg format doesn't support transparency, so conceptually you will have to:

• grab the pixels from the larger image (the jpeg) and put them into a buffer
• grab the non-transparent pixels from the smaller image (the watermark) and move them into that buffer, applying the alpha along the way

You probably want to let a library do this. I like ImageMagick, especially since it's built in to php... here's an example of how to use it for this purpose from PHP:

// Let's read the images. 
$glasses = new Imagick(); 
if (FALSE === $glasses->readImage($dir . '/glasses.png')) 
{ 
    throw new Exception(); 
} 

$face = new Imagick(); 
if (FALSE === $face->readImage($dir . '/face.jpg')) 
{ 
    throw new Exception(); 
} 

// Let's put the glasses on (10 pixels from left, 20 pixels from top of face). 
$face->compositeImage($glasses, Imagick::COMPOSITE_DEFAULT, 10, 20); 

And here's the link to the PHP manual page for ImageMagick::compositeImage (from which the above example came).