I have followed the instructions from this link:
https://docs.cocos2d-x.org/creator/manual/en/render/camera.html (Screenshot part)
and have successfully captured a specific node with Cocos Creator 2.1.2
However, after upgrading to 2.2, it seems that the captured image has been scaled down.
thx, We’ve received the same issue and it will fixed on v2.2.1