Change EXIF data in PHP

gistfile1.txt

require_once('/../pel/PelDataWindow.php');
require_once('/../pel/PelJpeg.php');

$filename = $_GET['file'];
// If your files are stored in a different directory, you'll want to add the directory structure here, before $filename
$file = $filename;
// This assumes you're using a form. Change the $caption as you'll need (if loop, etc.)
$caption = $_GET['caption'];

$pic = new PelJpeg($file);

/* Create and add empty Exif data to the image (this throws away any
 * old Exif data in the image). */
$exif = new PelExif();
$pic->setExif($exif);

/* Create and add TIFF data to the Exif data (Exif data is actually
 * stored in a TIFF format). */
$tiff = new PelTiff();
 $exif->setTiff($tiff);

 $ifd0 = new PelIfd(PelIfd::IFD0);
$tiff->setIfd($ifd0);

  $desc = new PelEntryAscii(PelTag::IMAGE_DESCRIPTION, $caption);

/* This will insert the newly created entry with the description
 * into the IFD. */
$ifd0->addEntry($desc);

//This overwrites the existing file. Change the location if you want to save a copy
$pic->saveFile($file);