Adjust PDF resolution in Rhino.Inside.Revit

I’m trying to import several PDF files to Revit through Rhino.Inside.Revit by using Add Image. I want to increase the resolution of PDF in RiR but it seems the resolution is read only parameter and cannot change.
Is there anyway to do it? Thanks a lot!

Correct, that property is Get only

Instance Scale and Width/Height are available for modifications

I see. Thank you so much for your response.
But when I increase Scale or Width/Height, the quality of PDF is still the same. It seems the only way to improve its quality is changing the resolution.