How to save 16bit rgb and depth from Zbrush 2,5d canvas ?

gnoop

I know there is grab brush that saves depth as alpha  and  rgb separately  but you have to do save two times  instead of just once.   It's extremely annoying   and also when you try to record this save  in a macro action it often  does  less than the whole document  for some uncertain reason.  My guess probably  by exactly same frame when it was recordered.     Besides macro recorder exports  not for the last /current grab but rather same old one you did  when recordered the macro. 

There is "grab unshaded doc RGB +depth"   in texture panel but it exports  as 8 bit PSD only . 

There is zbrush to Pshop plugin  . It also saved 8 bit  only . Same with Zaplink .

Is there any simple  way to grab the whole doc in its exact pixel dimensions and save as 16 bit PSD + depth in alpha?    Maybe by special script command?    Not wasting time to render anything or calculating displacement forever?  just grab exactly 2kx4k  for example?      Maybe a third party tool to parse ZBR file ?