Word expects pictures to be at 96 dpi. If you import a graphic at some other
resolution, Word re-sets the size accordingly: eg, if the original is 5 cm
wide x 300 dpi, Word will display it as 15.625cm wide (ie 300/96 x 5).
However you can then resize the graphic within Word, which changes the
effective resolution. If you then save the document as HTML, the graphic
file created will be at the original size and resolution, not the scaled
size.
In other words, there's no easy way to determine it other than saving the
document as HTML to get the original size and resolution; then divide the
original resolution by the ratio of the original and effective sizes.
