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

["honyk" <j.tosovsky@email.cz>]

Recently I've been surprised by different size of legacy GIF files and PNG
equivalents of the same files in PDF file generated using XEP. It was clear
it is caused by resolution, which is stored in PNG but not in GIF. In
http://www.renderx.com/reference.html#Bitmap I've found GIF resolution is
considered as 120 dpi by default while resolution of my PNG files was lower,
depending on monitor resolution of computer on which they were taken (it was
in range 80-115 dpi).

To keep the same resolution of screenshots in the whole document there were
two ways. The first one to take all screenshots again on the same computer
(to ensure the same resolution) or save them as GIF insterad of PNG (discard
resolution information so it will be considered as 120 dpi as default).

I've used third solution. Using library ImageMagick I've inserted one step
just before FO transformation, where resolution of all PNG images is set to
120 dpi, so it is equal to final GIF 'resolution'.

Jan

> -----Original Message-----
> From: Daniele Barzotti [mailto:daniele.barzotti@eurocomtel.com] 
> Sent: Wednesday, August 05, 2009 6:01 PM
> Cc: docbook-apps@lists.oasis-open.org
> Subject: Re: [docbook-apps] PNG Images rendering on XML->FO->PDF
> 
> Rowland, Larry ha scritto:
> > ...
> > 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.
> > 
> 
> Thanks a lot for your explanation Larry!!
> You were very clear!!
> 
> For now I've solved the 'problem' using different stylesheets putting
> 
> <xsl:param name="ignore.image.scaling" select="1"/>
> 
> inside the one to create html output.
> 
> Cheers,
> Daniele.