php codeigniter文本水印不来了

Question

在PHP的CodeIgniter中，文本水印消失了。在代码之后，它显示成功，但是当我检查输出图像时，文本未显示。

    $this->load->library('image_lib');
    $config['image_library'] = 'gd2';
    $config['source_image']='./uploads/user_certificates/certificate_model.jpg';
    $config['new_image']='./uploads/user_certificates/test5.jpg';
    $config['wm_text']='sample text';
    $config['wm_type']="text";
    $config['wm_font_path']="./assets/frontend/webfonts/fa-regular-400.ttf";
    $config['wm_font_size'] = 46;
    $config['wm_font_color'] = '#453344';
    $config['wm_vrt_alignment'] = 'top';
    $config['wm_hor_alignment'] = 'left';
    $this->image_lib->initialize($config);
    $this->image_lib->watermark();
    //$this->image_lib->initialize($config);
    if (!$this->image_lib->watermark()) {
        echo $this->image_lib->display_errors();
    } else {
        echo 'Successfully updated image with watermark';
    }