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

[MORREALE Jean Roc]

Jacolin Yves a écrit :
> 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.

Thanks Yves, if you can please do so as I am not familiar with all that 
latex makefiles' wizardry.