Watermark on Uploaded Image Using PHP

**vishal** · 01-11-2010 12:04 PM

This tutorial shows you how you can add a watermark image over images that are uploaded though a form.
The following is a html code as simple as it can be with an image type input and a Submit button:

Code:

<form name="image" method="post" enctype="multipart/form-data"  action="">

<input type="file" name="image">
<input name="Submit" type="submit" value="Upload ">

</form>

This is the function that applies the watermark over the uploaded picture and uploads the picture on the server.

Code:

function copy_marked($img_name,$newname,$type)
{
// check image type. The image type is sent as parameter 3 ($type). Note that for every image type a different function is used to create an image in memory from the uploaded file.


   if(!strcmp("image/jpg",$type) || !strcmp("image/jpeg",$type) || !strcmp("image/pjpeg",$type))
        $src_img=imagecreatefromjpeg($img_name);

    if(!strcmp("image/png",$type))
        $src_img=imagecreatefrompng($img_name);

    if(!strcmp("image/gif",$type))
        $src_img=imagecreatefromgif($img_name);

// get image size, we'll need it later
    $old_x=imageSX($src_img);
    $old_y=imageSY($src_img);

// create destination image
    $dst_img=ImageCreateTrueColor($old_x,$old_y);

    imagecopyresampled($dst_img,$src_img,0,0,0,0,$old_x,$old_y,$old_x,$old_y);

    // on this demo, the watermark image will be named watermark.gif and will be located in images folder. If you intend to use other file, you will have to change this
    $watermark_file='images/watermark.gif';

// you can setup the transparency used for watermark image.
    $transparency=50;

// just in case you don't know what extension the watermark file has. This function is listed lower
   $wext=getFileExtension('images/watermark.gif');

// create an image from watermark file
    if(!strcmp("jpg",$wext) || !strcmp("jpeg",$wext)) $watermark=imagecreatefromjpeg($watermark_file);

    if(!strcmp("png",$wext)) $watermark=imagecreatefrompng($watermark_file);

    if(!strcmp("gif",$wext)) $watermark=imagecreatefromgif($watermark_file);

// get watermark width
    $watermark_width = imagesx($watermark);
    $watermark_height = imagesy($watermark);

// place watermark image on the right left of the main image
    $dest_x = $old_x - $watermark_width - 5;
    $dest_y = $old_y - $watermark_height - 5;

 // uncomment these lines and comment the ones above if you want to place the watermark in the very center of the image
//    $dest_x = (($thumb_w - $watermark_width)/2);
//    $dest_y = (($thumb_h - $watermark_height)/2); 
 
// merge the two images
   imagecopymerge($dst_img, $watermark, $dest_x, $dest_y, 0, 0, $watermark_width, $watermark_height, $transparency);

 // copy the new created image to the destination file, in the images folder
    if(!strcmp("image/png",$type))  imagepng($dst_img,$newname);

    else if(!strcmp("image/gif",$type))  imagegif($dst_img,$newname);

    else imagejpeg($dst_img,$newname);
        
// delete the images from memory
    imagedestroy($dst_img);
    imagedestroy($src_img);

}

Code:

Function getFileExtension(), needed to get the file extension:
function getFileExtension($str) {
        $i = strrpos($str,".");
        if (!$i) { return ""; }
        $l = strlen($str) - $i;
        $ext = substr($str,$i+1,$l);
        return $ext;
}

Having all these functions, here is how you verify if the form was submitted and call the copy_marked() function to upload the file and place the watermark:

Code:

if($_SERVER['REQUEST_METHOD']=='POST')
{
    if ($_FILES['image']['name']) 
    {
        $image=$_FILES['image']['name'];
         $newname="http://forums.x10hosting.com/images/".$image;
        copy_marked($_FILES['image']['tmp_name'],$newname,$_FILES['image']['type']);
    }    
}