You「ll indicate that it」s a PNG image because this call can actually insert PNG and JPEG images (if you have the GD library installed in your PHP setup, it can also load any image supported by GD).
您将要说明它是一个png图像,因为此调用实际可以插入PNG和JPEG图像(如果在您的php安装中已安装了gd库,则其也可以加载任何由GD支持的图像)。