[Image-SIG] .DCX files and dpi information

[Larry Bates]

I have some incoming fax files in .DCX format.  I need to obtain the 
horizontal and vertical resolutions and number of pixels for each page
that is stored in a separate file.  I tried:

import image
i=Image.open("file001.dcx")
hres, vres=i.info

i.info returns (1728, 2159) which is pixels of horizontal and vertical
dots on the page.  

Question: How can I obtain the resolution (e.g. dpi) of the pixels as
they are encoded in the file?  The faxes can come in in either 100
or 200 dpi vertical resolution (e.g. fine setting on fax machine) and
I need to handle each differently.

Thanks in advance for any help.

Regards, 
Larry Bates