private function createBlank($width, $height)
    {
        $blank = imagecreatetruecolor($width, $height);

        /**
         * This is not ideal when converting png to jpeg as instead of a default
         * black background we end up with a white one.
         * This is alleviated by additional use of imagecopyresampled() before
         * outputting jpegs.
         */
        if ($this->getMime() === 'image/png') {
            imagealphablending($blank, false);
            imagesavealpha($blank, true);
        }

        return $blank;
    }