How to remove the redundant part of an image ?

CAD has provided CLIP command which can be used to clip company logo, which is relatively regular in shape. But when it comes to a plant, a person or building, it would be much more inconvenient to use the CLIP command.

How to clip block, Xref, image or viewport?

CAD system has different clip commands for different objects: to clip image, the command is IMAGECLIP; to clip viewport, the command is VPCLIP; to clip block and Xref, the command is XCLIP.