Re: Image resolution for PDF

Jean-Marc van Leerdam wrote:
> Steve,
>
> On 05/04/2008, *Jean-Marc van Leerdam* <j.m.van.leerdam_at_gmail.com
> <mailto:j.m.van.leerdam_at_gmail.com>> wrote:
>
> Steve,
>
> On 05/04/2008, *Stefan Küng* <tortoisesvn_at_gmail.com
> <mailto:tortoisesvn_at_gmail.com>> wrote:
>
> Jean-Marc van Leerdam wrote:
>
> Hi,
>
> The recent changes to the way the documentation is generated
> has resulted in reduced quality images in the PDF version.
> On screen they look fine, but printing them results in --
> how do I say this nicely -- sub optimal prints ;-)
>
> I noticed a commit where all images were reduced to 96dpi
> and a max width/height of 500/800. This results in a max
> effective image width in the PDF of 5.2 inch (13 cm).
>
>
> The dpi was not reduced. Most images already had a dpi of 96,
> but some had one of 72dpi. those were increased to 96 dpi.
>
>
> When setting the dpi to 150 on the .png files, they render much
> nicer in pdf (no other changes needed).
>
> I don't expect this will impact the html and chm rendering, as these
> use the images as they are right?
>
> I can post the TortoiseSVN-1.5.0-en.pdf if you want to see the results.
>
> Images up to 800 pixels wide will fit onto a page if its DPI is set
> to 150.
>
> Isn't it possible to render the images as 200dpi (or 150dpi)
> in the PDFs? With a max width of 13 cm, that should allow
> images of up to 1040 (or 780 at 150dpi). For printouts that
> results in much clearer images.
>
> I would lend a hand in debugging the FOP/Docbook stuff to
> see where the image resolution is set. A pointer towards the
> file(s) to start with would be great.
>
>
> If you can find out how to make the pdf generation scale the
> images to fit the page so they won't get cut off at the right,
> that would be great. I tried many hours to get this done without
> success.
>
>
> Scaling oversized images is not available in FOP at the moment. See
> http://xmlgraphics.apache.org/fop/knownissues.html (Other known
> issues, bullit 11: Images currently don't shrink so they fit on a
> page when they are too big and shrinking is allowed to happen).
>
>
> But if we really want to include a larger image, we just have to set
> it's DPI to a higher value. That way, the image will fit on the page and
> still show the required detail when printing (or by zooming in when
> viewing the PDF).

The problem with this approach is that we'd have to check this for every
single image (and there are a lot of them) to find a dpi which makes it
fit on a page.

But if you have some time to do this, be my guest :)

Stefan

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