imagemagick - Cut rectangle from the image

Question

I have a png image. How can I cut a small rect from this image using imagemagick? (make a transparent hole in image)

For example:

Source:

Destination:

Answer 1

看来我想通了。

convert u1.png -alpha set -region 40x30+15+5 -alpha transparent u3.png

它从 u1.png 切出一个矩形（40x30）