[Qgis-community-team] compiling manual & image quality

[Jacolin Yves]

Le Friday 21 August 2009 14:36:15 MORREALE Jean Roc, vous avez écrit :
> Otto Dassau a écrit :
> > On Fri, 21 Aug 2009 13:11:40 +0200
> >
> > MORREALE Jean Roc <jr.morreale at enoreth.net> wrote:
> >> Otto Dassau a écrit :
> >>> Hi Jean Roc,
> >>>
> >>> On Fri, 21 Aug 2009 11:04:10 +0200
> >>>
> >>> MORREALE Jean Roc <jr.morreale at enoreth.net> wrote:
> >>>> Hi,
> >>>>
> >>>> I've been compiling the french manual for 1.0 (using texlive2008) but
> >>>> the quality of the images is very low : the jpg figuring in the final
> >>>> pdf are full of compression blocks making some captures hard to read.
> >>>>
> >>>> All the source's images have been localized and saved as png (96dpi)
> >>>> so I would really like to have them show up in a better quality.
> >>>>
> >>>> What are the right options to change ?
> >>>
> >>> All images are simply converted during compilation without any change
> >>> of size or
> >>> resolution. In the english version, many figures are screenshots with
> >>> only 72dpi
> >>> resolution. You are right they sometimes could be better, but I don't
> >>> know of
> >>> any parameter for dvipdf or dvips conversion that make the images look
> >>> better,
> >>> except using images with a higher resolution - just my 2c.
> >>>
> >>> Regards,
> >>>  Otto
> >>
> >> Hi Otto,
> >>
> >> It is not a matter of size or resolution but of jpeg artifacts due to a
> >> drastic compression, when I compare the png/eps they do not show these
> >> blocks but the jpgs included in the pdf are full of it. I think  the
> >> quality setting used by convert is below 60%, if we could get it up to
> >> 75% the images would be less blocky and still around 5% of the size of
> >> the pngs
> >
> > Hi Jean Roc,
> >
> > ok, but since the pdf figures are created from eps format, I wonder where
> > we can improve the process since b) uses eps files created in a):
> >
> > a) convert PNG and JPEG to EPS defined in the Makefiles
> > b) create a PDF with dvipdf (a combination of dvips and ps2pdf) using EPS
> > figures from a)
> >
> > and when I look at the branches/1.0.0/french/user_guide folder, I don't
> > see any jpeg images except the qgis logo on the front page, or am I
> > wrong?
> >
> > Can you give an example image where you think there is a big quality
> > problem?
> >
> > Regards,
> >  Otto
>
> For example take a look at startup1.0.0.png and the image as it appears
> in the pdf (here saved as a jpg but could have been exported as a tiff
> with the same defects), you can see color distorsion and noise which are
> typical of an heavy quantization step:
>
> http://uppix.net/5/e/6/4197c43cfb28e319c4889368f40cd.png
> http://uppix.net/d/a/b/83b44bd238113703618b279045a45.jpg

Hello,

After looking in Google, it seems that dvipdf is known as not be the best way 
to create PDF file with nice picture. Some people advice to use latex2pdf.

Jean-Roc, could you test it this afternoon, or do you prefer Iet me test to 
build to night ? :)

Y.
-- 
Yves Jacolin

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