To increase graphic resolution of diagram's published output image file

[avi10000]

Hi all,
I am using v15.1. How do you increase the Graphic Resolution of a diagram's published output image file?
In my EA, you export a diagram by: Publish > Save > Save to File.
But the outputs I have been getting don't seem to me to be high enough resolution.
Where is the setting to increase the resolution?

I found this Q that asks the same thing:   
   https://sparxsystems.com/forums/smf/index.php?topic=25518.0
but it was a long time ago and the answer does not seem to be appropriate for my EA version.

Thanks
Avi

[avi10000]

I found also this thread:

Save to File - Is there any way of increasing the resolution of the PNG output?
https://sparxsystems.com/forums/smf/index.php/topic,46164.msg270244.html#msg270244