Sharp images from Apple Keynote coming out blurry on Zoom (in Portion of Screen mode)

[CarlHoney]

Hello, 

I share Apple Keynote presentations via Zoom. I am running the latest Mac OS and the latest version of Zoom.

The images inside Keynote are all high-resolution and look pin-sharp on my MacBook all the time I'm sharing. But they come out blurry on the other end when I share a Portion of Screen on Zoom.

This happens every time. No matter how many people are in the Zoom (from one person to hundreds).

This is NOT a problem with the internet or WiFi connection. Because I have tested it on super-fast networks and even with computers sitting side by side on the same desk.

I have spoken to an Apple specialist and they cannot find a problem on the Apple end. So the problem must be with Zoom.

I have noticed that when I share my full MacBook screen in Basic mode on Zoom, the images come through to the audience in crisp resolution.

But as soon as I move to sharing only a Portion of Screen (in Advanced mode), the resolution falls off and everything blurs and pixelates a little.

I want to run Keynote in Presenter Mode so that the audience only sees a portion of the screen  (ie. current slide) and only I can see the next slide and notes.

But as soon as I move from Basic Mode (full-screen share) to Advanced mode (sharing only portion of screen) the images all go lower resolution and a bit blurry.

Which is weird. Because you'd think that sharing a smaller part of the screen would make the resolution even better!

Still, the problem clear lies in moving from sharing my entire screen to sharing just a portion.....

Any ideas how to fix this? Is there a setting I can tweak? Or is loss of image quality inevitable when sharing a portion of my screen through Zoom?

Thanks!

Carl