Creating a thumbnail of an image with alpha/transparency

    /**
     * This accepts two parameters, the file path to the image that you want
     * to create a thumbnail of ($file) and the directory path and file name
     * where you want to put the thumbnail ($directory).
     * For the purposes of this module, the directory path to the images are:
     * ../images/mypictures/example.jpg
     * and the place to put the thumbnail is:
     * ../images/mypicturesthums/thumb_example.jpg
     * Returns true if everything has worked out okay, false if there has been
     * a problem when calling the function
     * @param string $file
     * @param string $directory
     **/
    public function createThumb( $file='', $directory = '' ) {
        // Booleans used to set the type of images that we'll deal with later
        // (all false by default):
        $jpeg = false; $png = $jpeg; $gif = $jpeg;
        // Gets the type of image from the array:
        $type = $this->imgData['exts'];
        // Checks for each case to ensure that the relevant filetype is called:
        switch($type) {
            case 'gif':
            $img = imagecreatefromgif($file);
            // Checks for transparency:
            $transparentIndex = imagecolortransparent($img);
            if($transparentIndex!=(-1)) {
                $transparentCol = imagecolorsforindex($img, $transparentIndex);
            }
            $gif = true;
            break;
            case 'jpeg':
            case 'jpg':
                $img = imagecreatefromjpeg($file);
                $jpeg = true;
            break;
            case 'png':
                $img = imagecreatefrompng($file);
                // Checks for alpha channel:
                imagealphablending($img, true);
                imagesavealpha($img, true);
                $png = true;
            break;
            default:
                return false;
            break;
        }
        // This should be the same as saying $newX = imagesx($img)/8, but might
        // be a bit quicker:
        $newX = imagesx($img) >> 3;
        $newY = imagesy($img) >> 3;
        // Creates instance of thumbnail at 1/8 the size, and scales the parent image appropriately:
        $small = imagecreatetruecolor($newX, $newY);
        imagecopyresampled($small, $img, 0, 0, 0, 0, $newX, $newY, imagesx($img),imagesy($img));
        // Saves new image according to type:
        if($jpeg) {
            imagejpeg($small, $directory, 100);
        } else if ($gif) {
            imagegif($small, $directory, 100);
        } else if ($png) {
            imagepng($small, $directory, 100);
        } else {
            // If no boolean is set then something has gone wrong:
            return false;
        }
        // Releases resources:
        imagedestroy($img);
        imagedestroy($small);
        // You success:
        return true;
    }