How to adjust picture properties embedded into Powerpoint?

I have no experience with generating Powerpoint output with Matlab and have looked up the very minimal basics to get me going. I find that what I embed into a .pptx isn't giving me the desired output - to begin with, the size/aspect ratio. Here is an example:

import mlreportgen.ppt.*
splot = Picture('ABC.png');
splot.Width = '800px'; splot.Height = '480px';
pictureSlide = add(ppt, 'Title and Picture');
replace(pictureSlide, 'Picture', splot);
close(ppt);

This does not produce the desired aspect ratio in the .pptx. The original png was saved as 800x480. Alternatively, using .Width = '5in' & .Height = '3in' doesn't change things either. The embedded picture is very wide-format and seems to be a best-fit for the slide area, maybe conforming to what a picture placeholder would be. There is no other Powerpoint related code in the script and no templates or anything being loaded or created.

In short, is there a way to simply embed the picture while preserving the original aspect ratio of the png image?

[Jessica Johnson]

Were you ever able to resolve this? I find myself with the exact same problem. Thanks