我正在尝试从外部网址复制图片，请提供帮助。
convert -quality 80 https://s-media-cache-ak0.pinimg.com/564x/46/70/6c/46706c1cbf3e505a2b4abf99eee0fe02.jpg /home/user/public_html/files/test.jpg
SSH错误输出：
convert: not authorized `//s-media-cache-ak0.pinimg.com/564x/46/70/6c/46706c1cbf3e505a2b4abf99eee0fe02.jpg' @ error/constitute.c/ReadImage/453.
convert: missing an image filename `/home/user/public_html/files/test.jpg' @ error/convert.c/ConvertImageCommand/3015.