[daip] beam size in pixels

[Casey Law]

Hello daip,
	I have a simple question that I can't find the answer to in the
help files.  I am trying to calculate the beam size in pixels for an
arbitrary image.  AIPS does this with IMSTAT, but only for VLA images.  
This is probably a header thing, but really I'd just like to know the
general form.
	My naive calculation is like this:
 pix_area/beam_area = pixsize^2/(pi*bmaj/2*bmin/2)

but this gives an answer that is smaller than the value output by IMSTAT
by a factor of 0.69.  For example, in one case, I calculated that the beam
area as 25.7 pixels, but IMSTAT says "Beam area = 37.09 pixels".
	Can you tell me the proper way to calculate the beam area in
pixels?

		Thanks!
		casey