Add a gradient / mirror effect to an image

This code creates a 3D gradient / mirror effect on the bottom on an image, similar to the Mac tool bar.
It takes the parameter file which is a URL to a JPG image ( please note this script only handles JPG images ). You could use a mod_rewrite to alias this in the URL itself or to a local image cache on your server.
<?php
      define ( 'IMAGE_FLIP_HORIZONTAL', 1 );

        define ( 'IMAGE_FLIP_VERTICAL', 2 );

        define ( 'IMAGE_FLIP_BOTH', 3 );
      $main_file = $_GET["file"];
$imgImport = imagecreatefromjpeg($main_file);
      $imgName_w = imagesx($imgImport);

        $imgName_h = imagesy($imgImport);
      // How many pixels to add to the left and right

        $expand = 30;
      // How deep to make it

        $depth  = 30;
      // Transparency level to start from

        $transparencyFrom = 80;
      // Transparency level to end up with

        $transparencyTo   = 0;
      $newImage = imagecreatetruecolor($imgName_w + $expand*2, $imgName_h + $depth);
      $gdGradientColor=ImageColorAllocate($newImage,255,255,255); 
      imagefilledrectangle($newImage,0,0,$imgName_w + $expand*2,

                            $imgName_h + $depth, $gdGradientColor);
imagecopymerge($newImage, $imgImport, $expand, 0, 0, 0,

                     $imgName_w, $imgName_h, 100); 
      $flippedImage = ImageFlip( $imgImport, IMAGE_FLIP_HORIZONTAL );
      $iter = $expand / $depth;
      $tmpImage = imagecreatetruecolor($imgName_w + $expand*2, 1);
      $transparencyIterations = ($transparencyFrom - $transparencyTo) / $depth;

        $expanding = $expand ;
      for ($y = 0; $y < $depth; $y++)

        {

            imagefilledrectangle($tmpImage,0,0,$imgName_w + $expand*2,1, $gdGradientColor);

            imagecopyresized( $tmpImage ,$flippedImage, $expanding, 0, 0, $y ,

                      $imgName_w+(($expand-$expanding)*2),1, $imgName_w,1 );

        

           imagecopymerge($newImage,$tmpImage,0,$y + $imgName_h,

                   0,0,$imgName_w + $expand*2, 1,$transparencyFrom);
           $transparencyFrom -=  $transparencyIterations;

            $expanding 		  -= $iter;

        }
      imagecopyresampled($imgImport,$newImage, 0, 0, 0, 0 ,$imgName_w,$imgName_h, 

                          $imgName_w + $expand*2, $imgName_h + $depth );
      header("Content-type: image/jpeg");
      imagejpeg($imgImport, '', 80); //100 being the quality of image 100 Max(Best)
      imagedestroy($newImage); 

        imagedestroy($tmpImage); 

        imagedestroy($flippedImage); 

        imagedestroy($imgImport); 
      // Image flip - not my code, from the PHP examples
      function ImageFlip ( $imgsrc, $mode )

        {
           $width                        =    imagesx ( $imgsrc );

            $height                       =    imagesy ( $imgsrc );
           $src_x                        =    0;

            $src_y                        =    0;

            $src_width                    =    $width;

            $src_height                   =    $height;
           switch ( (int) $mode )

            {
               case IMAGE_FLIP_HORIZONTAL:

               $src_y                =    $height-1;

                $src_height           =    -$height;

                break;
           case IMAGE_FLIP_VERTICAL:

               $src_x                =    $width;

                $src_width            =    -$width;

                break;
          case IMAGE_FLIP_BOTH:

                $src_x                =    $width;

               $src_y                =    $height;

               $src_width            =    -$width;

               $src_height           =    -$height;

               break;
          default:

                return $imgsrc;
           }
           $imgdest                    =    imagecreatetruecolor ( $width, $height );
           if ( imagecopyresampled ( $imgdest, $imgsrc, 0, 0, $src_x, $src_y, 

                                     $width, $height, $src_width, $src_height ) )

            {

                return $imgdest;

            }
           return $imgsrc;
      }
      ?>