I do lots of graphics in simulations, schematic layout and other areas
of my work. 640x480 works for photos, but not for high end graphics.
I routinely send my co-workers schematics encoded at 1920x1280 because
the small lines, some text and often critical details vanish at larger
pixel sizes or become unreadable.
I do not use PDF, but often PNG or JPEG as the exported file format
because they retain more data.
When one works with highly technical data and graphics, more detail is
warranted for publishing. IF it is to go into print, the added detail
allows the printing service to edit the pictures because they can see
all the content and you can tell them if any or all aspects are crucial
to understanding the document.
Many people do not understand the relationship between screen resolution
and sensor resolution and image quality. You still see many "home made"
videos even from large companies that do not recognize that screen
reproduction requires some rendering software to ensure no loss of
context or vital information.
A resolution of 640x480, even at 5x7 actually presents data that is
fuzzy to look at in the details. It is Minecraft 2.0 graphics at best.
Another example is when 640x480 information is in a slide presentation
which is then projected onto a screen that is say 6'x4', and each pixel
becomes about 0.1" in size. If you are say 5 feet from the screen, not
uncommon in most conference rooms, the data looks fuzzy at best.
For a technical person this is hardly a testament to their skills at
using technology.
Regards,
Les H