[Scribus] Image export dpi problem

[scirbus at tovel.it]

Hi to all,
I'm new to the list.
I post here for more clarifications before (eventually) fill a bug
report.

I try to use scribus for a photo poster composition.

The printer supports only bitmap files.
The printer supports a resolution of 250 dpi.
The poster is 820x500 mm =~ 32.2x19.6 in
So the image export for the poster is around 8000x5000.

On Debian Gnu/Linux with
scribus 1.2.0.rc1
export jpeg
quality 100%
resolution 250 dpi
the output is (from identify)
xxx.jpeg JPEG 4921x3000 DirectClass 7.2mb 0.000u 0:01

On Debian Gnu/Linux with
scribus 1.2.1
export jpeg
quality 100%
resolution dpi 250
size 100%
the output is (from identify)
xxx.jpeg[1] JPEG 1417x863 DirectClass 912kb 0.000u 0:01

On Debian Gnu/Linux with
scribus 1.2.1
export jpeg
quality 100%
resolution dpi 250
size 600%
the output is (from identify)
xxx.jpeg JPEG 8504x5185 DirectClass 17.5mb 0.000u 0:01

Can someone explain this behaviour?

Unfortunately in all cases the quality of the image is far from optimal
both for images and text...
The text written with 12 pt font is quite unreadable...
If I open the image in Gimp and rewrite the same text the result is
perfect for the text.

I try to export a ppm and png with the same result.

I try to export in pdf and use convert pdf -> jpg with poor result.
Export pdf, print as ps with acroread, convert ... poor result.



Searching around I found only this bug report
http://bugs.scribus.net/view.php?id=1436
that is a feature request for define the image output in pixel and the
pixel as new native unit.

Could someone tell me where I'm wrong?
And which is the right way to export high quality images?

Thanks in Advance,
Daniele