protected function intermediateSizePortrait()
    {
        // Set height and then calculate width
        $this->intermediate['height'] = $this->canvas['height'];
        $this->intermediate['width'] = intval(round(
            $this->intermediate['height'] * $this->source['aspect_ratio'], 0));

        // If width larger than requested, set and calculate new height
        if ($this->intermediate['width'] > $this->canvas['width']) {
            $this->intermediate['width'] = $this->canvas['width'];
            $this->intermediate['height'] = intval(round(
                $this->intermediate['width'] / $this->source['aspect_ratio'], 0));
        }
    }