[xep-support] scale-when-image-is-too-big (reaction to...

[ronald heller]

Dear reader

The issue raised by my collegue Ronald is imho an important one, and I 
cannot agree (yet) with the statement made by David Tolpin. He states, if I 
understand correctly, that downscaling done by the PDF renderer is not 
something you'd choose because of the poor quality. The solution implied 
here is that you should downscale outside of the PDF renderer (and the PDF 
generator for that matter), and then include the image at 100% unscaled. 
This is highly unpractical: Consider allowing a publication to be created 
for and rendered on 7 paper sizes (a4, a3, letter, etc., at the convenience 
of the client): this would require 7 'versions' of the same images when 
e.g. page width is different in all cases! FO-based rendering would become 
very expensive indeed.

Images are created irrespective of the exact print medium (paper size, 
location on page, etc.). Especially in a POD environment you require the 
PDF generator to know what the exact dimensions of the rendering rectangle 
on page are or can be (which it actually knows!), and pass those dimensions 
along with the image content. There is no way you can do this outside the 
PDF generator, unless you specify all current idents, borders, line 
thicknesses, margins, what have you (all of which play a role in 
determining the image's size on paper) and add them all up, in advance. 
This 1/ is very cumbersome, 2/ actually extends the functionality of the 
PDF generator, and 3/ fails to work in situations where other measurements 
are calculated by the PDF generator itself (relative measurements and the 
like).

So, as far as I can see the XEP solution would not suffice for realistic 
print requirements due to limitations described....

Willing to learn,
as ever,

arjan


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