If your table has fixed cell widths and heights, any images you insert into it, other than by dragging or copying them from elsewhere in a document, will automatically resize to optimally fill the space available while retaining the correct aspect ratio.

As for "I do not want to go through every one and figure out the width and height for each cell and type in the corresponding values for every cell", to justify that on the basis of "it might take me one day" seems nothing more than a pretext. How else would you propose to do it?

__________________
Cheers,
Paul Edstein
[Fmr MS MVP - Word]