php , gd, create watermark, change watermark text size and background color, imagecreatefromjpeg

Question

I need to create a watermark apply it on a picture and save it with a different name . The current script works pretty well but the only problem is that I need to increase the size of the "sample text" and change the background from black to white . I tried different scenarios , changed the opacity but still can't change the background color . Any help would be highly appreciated

 function watermark($imag_path, $photo_id)
    {
// Load the stamp and the photo to apply the watermark to
$im = imagecreatefromjpeg("$imag_path");
echo "imag_path is $imag_path and photoid is $photo_id";
// First we create our stamp image manually from GD
$stamp = imagecreatetruecolor(490, 20);

//$im = imagecreatefromjpeg("$photo_id");
imagestring($stamp, 5, 20, 2, 'sample text, 0xff0000);

// 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);

// Merge the stamp onto our photo with an opacity (transparency) of 100%
imagecopymerge($im, $stamp, imagesx($im) - $sx - $marge_right, imagesy($im) - $sy - $marge_bottom, 0, 0, imagesx($stamp), imagesy($stamp), 100);
$new_photo_id = $photo_id."sample.JPG";
// Save the image to file and free memory
imagejpeg($im, "tmp/$new_photo_id");
imagedestroy($im);
   }

Answer 1

Why use a stamp at all? I use the following code on one of my sites:

  $im = imagecreatefromjpeg($path);

  function shadow_text($im, $size, $x, $y, $font, $text)
  {
    $black = imagecolorallocate($im, 0, 0, 0);
    $white = imagecolorallocate($im, 255, 255, 255);
    imagettftext($im, $size, 0, $x + 1, $y + 1, $black, $font, $text);
    imagettftext($im, $size, 0, $x + 0, $y + 1, $black, $font, $text);
    imagettftext($im, $size, 0, $x + 0, $y + 0, $white, $font, $text);
  }

  $font = '../fonts/verdana.ttf';
  $size = 11;

  # calculate maximum height of a character 
  $bbox = imagettfbbox($size, 0, $font, 'ky');
  $x = 8; $y = 8 - $bbox[5];

  $text = 'text to be added';
  shadow_text($im, $size, $x, $y, $font, $text);

  header("Content-Type: image/jpeg");
  imagejpeg($im, null, 90);

This code runs fast enough that we use it to add dynamic labels on the fly to photos from our photo section as they're downloaded, rather than save them to disk.