[Scribus] Transparent tif bug and related thoughts

[Aurelien]

Hi !

I've been reporting a bug yesterday evening about a problem occuring
when exporting to pdf a project with transparent tif downsampled in.
The bug is here : http://bugs.scribus.net/view.php?id=5402.


After discussing with some of you on irc chat, I've been trying to
resample my image at the fine resolution in Gimp (which is supposed to
be better to do that), and then put them in scribus without using the
resampling option of the pdf export.

Here, I've to precise on what types of files I'm working on.
I'm doing a poster, sized 84x59.4cm? (DIN A1) @ 300 dpi (it's the
printer agency settings). This poster contains a big transparent tif
which is the background, and a few little transparent and
non-transparent tif for the logos, etc.

My Machine is an AMD64 3700+ with 2Gb DDR, X800 GTO 16 graphic card,
under Debian AMD64 SID with scribus-ng 1.3.3.8.

I use no compression at all and the highest quality both in scribus and
Gimp.


Firstly I've tried to use a version of the background @ 150 dpi.
So in the pdf export option, I've set resample image to 300 dpi.
This export took a few seconds (10 max), and gave a 72Mb file.


Then, I've tried resampling this image from 150 to 300 dpi with the
Gimp. It took me 29 minutes to resample and save this image in tif
format. The tif generated weights 272Mb.
I put this image in my scribus project, I've unset the resample option,
and I've exported it. It took something like 30-40 seconds, and
generated a 275Mb file.


So, there's something I don't understand. I'm supposed to do almost the
same thing here, but with two different ways. I'm supposed, finally, to
get an image sizing 84x59.4cm? @ 300 dpi.
How can the two files be so different (weight), and why does Gimp takes
so much time to do what scribus do in a few seconds ?
And, prehaps a more pertinent question is : what does really do the
resampling option of scribus ?

Any ideas ?

-- 
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ORL (alias Yvette H.)