RE: [docbook-apps] PNG Images rendering on XML->FO->PDF

["Rowland, Larry" <larry.rowland@hp.com>]

Daniele,

>> Moreover I don't understand why the FO processor stretch the images
>> instead using their original size!

Part of this is because the size of a PNG has much to do with the way
the image is viewed.  Another is that not all PNG creation tools store
an accurate resolution in pixels per inch (or meters or whatever).
Some FO renders assume 72 pixels per inch, and some PNG creation tools
use the 72 pixels per inch value, regardless.  

You might want to check the resolution of the PNG images you are using.
You can open the image in something like GIMP and check the image
properties.  Many screen captures I have on my system have defaulted
to 72 pixels per inch, since the screen capture utility on Windows
that was used does not have a calibration mechanism and assumes all
screens are the same pixel density.  We always scale images and almost
always provide duplicate imageobject elements inside a mediaobject to
allow different scale factors for the images in HTML and FO output,
as described here in Bob Stayton's book on XSL:

  http://www.sagehill.net/docbookxsl/GraphicSelection.html

By the way, if you are trying to use DocBook for any significant
publishing effort, Bob's book is extremely valuable.

The 72 pixel per inch assumption caught us when we were first putting
our PDF render system together, but was easy to overcome once we
understood what was causing the problem.

Regards,

Larry

=======================================================================
[ Larry Rowland             | If you want to build a ship, don't drum ]  
[ ESS/ATG                   | up the men to gather the wood, divide   ]
[ Hewlett-Packard           | the work, and give orders. Instead,     ]
[ 3404 East Harmony Road    | teach them to yearn for the vast and    ]
[ Fort Collins, CO  80528   | endless sea. - Antoine de Saint Exupery ]
[ Phone: 970/898-2280       +-----------------------------------------]
[ E-Mail:larry.rowland@.hp.com                                        ]
=======================================================================