I'll just update what I stated a
long time ago
overlay mode 1: jpg ok, both P/shift+P give original size
overlay mode 2: nothing (well in my case it's black pictures with previously displayed OSD messages)
no overlay: jpg ok, original size + what you see ok
VRM9: bmp only, original size only
RGB overlay: couldn't test it, not supported on my Geforce2mx it seems; I'll try on a newer ATI tomorrow I suppose
if you have different results... please tell ;)