thanks for the suggestion, jayanta.  i tried it, but the results didn't improve much.  here are some screenshots to illustrate the problem.  i wonder if i am just not using the tools right.  i added a D size layout (very big paper).  i added the map (light gray canvas) to the layout.  i exported using ping and 1000 DPI.  that should give something like 24,000 pixels in height since D size is 24".  i used 8 bit gray scale output.  the file is very big (16MB), but the png image is not good.  here are screenshots of the png export (first image here) and the screen i see in arcgispro map view (2nd image).  .  

the export seems to blur the image a lot, even though i choose high DPI.  the png file is 16MB, so the problem is not a lack of pixels. i tried various other output formats - bmp, jpg - but had similar results (both are a bit worse than png).  it seems like i must not have the export set up right, but there are only a few things to pick.  
i tried with very high (3000) DPI and E size layout and still got poor results.  the output png file was 190MB 
 but still the image is pretty blurry.
i'd appreciate any suggestions you have
thanks!
j