Using command line changes attributes

[shiraz hashim <shiraz linux kernel gmail com>]

Hi,

While exporting a dia diagram from gui to png and
converting it from command line are giving different
results.

On exporting a diagram from gui, I can see

$ identify -verbose ex.png | egrep -i "resol|geom|pri"
  Geometry: 306x346+0+0
  Resolution: 72x72
  Print size: 4.25x4.80556
  Page geometry: 306x346+0+0

where as using command line tool, like

$  dia -t png -e ex.png ex.dia

I see,

$ identify -verbose ex.png | egrep -i "resol|geom|pri"
  Geometry: 304x344+0+0
  Resolution: 20x20
  Print size: 15.2x17.2
  Page geometry: 304x344+0+0

Why does resolution (pixel density) changes while using command line option.
This is blocking me to use dia run through a repository of dia images from a
Makefile.

-- 
regards
Shiraz Hashim