HOWTO: using Php to add watermark

makewatermark();

function makewatermark()
{
///////////////
// php imagemagick test harness
//
// create a watermarked image
///////////////

//xoffset of the watermark
//yoffset of the watermark

//the original image to be watermarked
$rawimage = NewMagickWand();
MagickReadImage( $rawimage, 'cyclops.gif' );
MagickWriteImage($rawimage, 'new_image.jpg' );
$originalimage='new_image.jpg';
//the watermark to apply
$watermarkimage = "sphinx.gif";

//top end opacity number (totally transparent)
$opacity0 = @MagickGetQuantumRange();

//bootom opacity (totally visible)
$opacity100 = 0;

//desired opacity percentage
// THIS IS THE ONE TO SET
$opacitypercent = 50;

//gather the actual opacity number
$opacity = $opacity0 - ($opacity0 * $opacitypercent/100 ) ;

//validate the opacity number
if ($opacity > $opacity0){
$opacity = $opacity0;
}elseif ($opacity <0){
$opacity = 0;
}

//initialize the wands
$sourceWand = NewMagickWand();
$compositeWand = NewMagickWand();

//read in the images
@MagickReadImage($compositeWand, $watermarkimage);
@MagickReadImage($sourceWand, $originalimage);

//setting the image index
MagickSetImageIndex($compositeWand, 0);
MagickSetImageType($compositeWand, MW_TrueColorMatteType);

//seting the opacity level
MagickEvaluateImage($compositeWand, MW_SubtractEvaluateOperator, $opacity, MW_OpacityChannel) ;

//combining the images
@MagickCompositeImage($sourceWand, $compositeWand, MW_ScreenCompositeOp, 0, 0);

//print out the image
MagickWriteImage( $sourceWand, 'new_image.jpg' );
//header("Content-Type: image/jpeg");
//MagickEchoImageBlob($sourceWand);
}
?>