Page 561 - Beginning PHP 5.3

Chapter 17: Generating Images with PHP

❑ Annotating the image with some descriptive text or a caption
❑ Copying a portion of another image into it to use as a watermark for copyright purposes

In the following sections you take a look at how to apply a watermark to an image, and also how to
create thumbnails of your images.

Applying a Watermark

If you are working on a Web site that displays original art or photographs, you may want to protect your
or your clients ’ intellectual property from being stolen. A common way of doing this is to apply a
watermark to the image to discourage other people from using it as their own. Here ’ s how to do it.
First, create a simple copyright image (such as Figure 17 - 17) in an image editor such as Photoshop. To do
this, add some black text to a white background and save the image as a PNG file with an eight - color
palette. (You see why this is done later in the section.)

Figure 17-17

Copying the Watermark into the Image
Here ’ s the script to create the watermarked image. Save this file as watermark.php . Figure 17 - 18 shows

an example result.
< ?php
$myImage = imagecreatefromjpeg( “lucky.jpg” );
$myCopyright = imagecreatefrompng( “copyright.png” );

$destWidth = imagesx( $myImage );
$destHeight = imagesy( $myImage );
$srcWidth = imagesx( $myCopyright );
$srcHeight = imagesy( $myCopyright );

$destX = ($destWidth - $srcWidth) / 2;
$destY = ($destHeight - $srcHeight) / 2;

imagecopy( $myImage, $myCopyright, $destX, $destY, 0, 0, $srcWidth,
$srcHeight );

header( “Content-type: image/jpeg” );
imagejpeg( $myImage );
imagedestroy( $myImage );
imagedestroy( $myCopyright );
? >

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