Darker but selected regions on image

[ziasumo]

On an image I want to make some rectangular region little darker ....
but only on more than one selected regions...

Or If I want to draw some rectangle or line on image but with opaque background color.

Thanks in advance

[fmw42]

see -region and -draw

http://www.imagemagick.org/Usage/draw/
http://www.imagemagick.org/script/comma ... php#region