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File size of photos in a screen share Powerpoint presentation


Hi, I wonder if anyone can help please.

I have a series of Powerpoint talks originally designed for 'in person' presentations via a projector and large screen. Because of this, the photographs used in the Powerpoint are high res largish file sized images [~4-5Mb]. I have recently been giving the same presentations over Zoom and showing the Powerpoint via screen share. On several occasions I have been informed by some of the attendees that there is often quite a time lag between what I as presenter have on my screen and what they as attendees can see - sometimes as long as ~20 seconds. This means that I am giving my spiel but it makes no sense as they have the wrong image.  I know our home wifi is a bit slow but I don't experience the same issue if I am an attendee at someone else's presentation. 

So I wondered if it would make any difference if I went through and replaced all the images with much lower file size versions suitable for viewing on a laptop?

I can't quite find out if what is transmitted via the internet to the attendees is the data from the Powerpoint presentation (and therefor a lot of data because of the image file size) or whether it is just a rendered version of what is showing on my screen and therefor just my screen resolution that is transmitted and the original file size is irrelevant?

I hope I have explained that well enough?? I assume the later and changing files will make no difference but wanted to check!




Community Champion | Customer
Community Champion | Customer

Nick, I think I can help. Without having to replace all your images in your PPT. Save your PPT with a new name - I don't want to mess up your original.  Check the file size of your original PPT so we can see much it was compressed. 

  1. Open PPT you just saved.
  2. Click one image
  3. Picture Format tab should appear in the Ribbon (see attached image)
  4. Click Compress Pictures (see attached image)
  5. Uncheck Apply only to this picture
  6. Click OK
  7. SAVE

Check your PPT file size

It should be substantially smaller than your original PPT.  Let me know if this works.



Hi Chris, thanks for this suggestion, it certainly reduced the file size considerably - sorry it took me a while to get back to you as I couldn't find the 'compress'  button on my system (tracked it down as it had not been added to the quick access tool bar.) Once found, it worked just as you said and has taken the presentation from 223Mb down to 49 Mb. I don't know yet whether that will speed up the slide changes in the presentation on Zoom.  So do you think this will have made a difference to the transmit time? I confess to not knowing how Zoom transmits the data (as I said above, is it really just a series of live screen shots or does the Powerpoint data get uploaded?)

Anyway, thanks for the help - I will wait and see if it has solved the time lag. Nick