[scribus] Aliasing and color problems

[Fabien SK]

Dear Scribus users and developpers,

I would like to do a photo book for an online photo lab. Since the user
interface of this lab (photoweb.fr) is not really convenient (limited
layout possibilities, slow web interface), I tried to do it with
Scribus. Once it's done (in fact I have already finished), I will export
it to jpeg images, upload it and put one jpeg per page, and then my book
will arrive at my home.
My book is simple: on each of the 100 pages, black blackground, one to
four images (from my 8 megapixel camera) with a slim white frame

As some people said before, using high-res images in Scribus is really
very memory-consuming (my process is between 2 and 3Gb heavy!), but it's
not my main problem for today.

I am using version 1.3.3.11 (ubuntu 8.04) on a AMD64, 2Gb of memory. I
am also trying to use a version I compiled from the HEAD of the svn to
get around my problems.

So, in version 1.3.3.11, when I export my pages to images (jpeg or png),
I get some aliasing. I cannot see it if I display the pages at their
actual paper size on my screen, but if I display it at 100%, I can see
it. Maybe it will be visible on the book, maybe not, but I would not
like to take the risk (money is money).
I could generate higher resolution images and scale them down.
Drawbacks:
- more manipulation could give useless loss of quality
- uses a lot of memory and disk space
If I export to a SVG and render it to an image (with rsvg or the gimp),
it looks fine. Drawback:
- I can only export one page at a time, so I would have to use my
developer skills to do it for all the pages
- Not user-friendly

Then I tried with the latest SVN version. The aliasing problem was gone!
But now, the black of the background is not black anymore. It's:
- 0-9-14-91 (?CMYK)
- 22-20-19 (RGB)


So if anyone could help me to solve one of these two problems, it would
be great:
- how to get around the aliasing in 1.3.3.11 in the image export
- how to make the black be black in 1.3.5 SVN

Cheers,
Fabien

[Gregory Pittman]

Post by Fabien SK
Dear Scribus users and developpers,
I would like to do a photo book for an online photo lab. Since the user
interface of this lab (photoweb.fr) is not really convenient (limited
layout possibilities, slow web interface), I tried to do it with
Scribus. Once it's done (in fact I have already finished), I will export
it to jpeg images, upload it and put one jpeg per page, and then my book
will arrive at my home.
My book is simple: on each of the 100 pages, black blackground, one to
four images (from my 8 megapixel camera) with a slim white frame
As some people said before, using high-res images in Scribus is really
very memory-consuming (my process is between 2 and 3Gb heavy!), but it's
not my main problem for today.
I am using version 1.3.3.11 (ubuntu 8.04) on a AMD64, 2Gb of memory. I
am also trying to use a version I compiled from the HEAD of the svn to
get around my problems.
So, in version 1.3.3.11, when I export my pages to images (jpeg or png),
I get some aliasing. I cannot see it if I display the pages at their
actual paper size on my screen, but if I display it at 100%, I can see
it. Maybe it will be visible on the book, maybe not, but I would not
like to take the risk (money is money).
I could generate higher resolution images and scale them down.
- more manipulation could give useless loss of quality
- uses a lot of memory and disk space
If I export to a SVG and render it to an image (with rsvg or the gimp),
- I can only export one page at a time, so I would have to use my
developer skills to do it for all the pages
- Not user-friendly
Then I tried with the latest SVN version. The aliasing problem was gone!
- 0-9-14-91 (?CMYK)
- 22-20-19 (RGB)
So if anyone could help me to solve one of these two problems, it would
- how to get around the aliasing in 1.3.3.11 in the image export
- how to make the black be black in 1.3.5 SVN

The whole point of Scribus is to *not* export to image files, but to
PDF. This should be your eventual format, and you can do this in
individual page files if you wish. Alternatively, exporting to EPS
should work, but PDF is far preferable.

Greg

[Tino Schwarze]

Post by Gregory Pittman

Post by Fabien SK
So if anyone could help me to solve one of these two problems, it would
- how to get around the aliasing in 1.3.3.11 in the image export
- how to make the black be black in 1.3.5 SVN

The whole point of Scribus is to *not* export to image files, but to
PDF. This should be your eventual format, and you can do this in
individual page files if you wish. Alternatively, exporting to EPS
should work, but PDF is far preferable.

You could also go the route Scribus -> PDF -> Ghostscript. I'm not sure,
Ghostscript can do CMYK JPEG, but then you might get arount that by
going Scribus -> PDF -> Ghostscript CMYK TIFF -> ImageMagick CMYK JPEG.

BTW: Are you sure the print shop won't do automated color correction or
something else? Did they provide a color profile for you to use, so your
RGB->CMYK conversion is correct?

HTH,

Tino.

[Fabien SK]

Post by Tino Schwarze
BTW: Are you sure the print shop won't do automated color correction or
something else? Did they provide a color profile for you to use, so your
RGB->CMYK conversion is correct?

Hi Tino,

The print shop allows optional automatic correction. I don't know yet
which option I will choose. I did not calibrated my screen (I don't have
any device to do so, and I don't know anyone who has one), and the last
time I ordered some prints (years ago), the non-automatically corrected
photos (I tried both) appeared too dark.
They provide an ICC profile, but I know about nothing about color
calibration and things like that, I'm just a basic user. My goal is just
to have a decent result.
?

Post by Tino Schwarze
The whole point of Scribus is to *not* export to image files, but to
PDF. This should be your eventual format, and you can do this in
individual page files if you wish. Alternatively, exporting to EPS
should work, but PDF is far preferable.

Well, the online print shop only accepts image files (it's more a
general public site than a shop for professionals), so I would like to
do like if I were ordering my original photos.

Thank you for your answers to both of you,
Fabien

[Tino Schwarze]

Post by Fabien SK

Post by Tino Schwarze
BTW: Are you sure the print shop won't do automated color correction or
something else? Did they provide a color profile for you to use, so your
RGB->CMYK conversion is correct?

The print shop allows optional automatic correction. I don't know yet
which option I will choose. I did not calibrated my screen (I don't have
any device to do so, and I don't know anyone who has one), and the last
time I ordered some prints (years ago), the non-automatically corrected
photos (I tried both) appeared too dark.

Well, I suppose, if they auto-correct your pre-layouted pages, things
might get pretty worse because there are multiple images in it (not so
with ordinary photos) and you've got a lot of black there. The images
might get very distorted.

Post by Fabien SK
They provide an ICC profile, but I know about nothing about color
calibration and things like that, I'm just a basic user. My goal is just
to have a decent result.

Which kind of ICC profile do they provide? CMYK, RGB? You should use
that in any case to do the RGB->PDF export. You don't need a calibrated
system for that. You should NOT try to export to "Printer" (=CMYK) PDF
without color management activated! The results will be very bad.

Post by Fabien SK

Post by Tino Schwarze
The whole point of Scribus is to *not* export to image files, but to
PDF. This should be your eventual format, and you can do this in
individual page files if you wish. Alternatively, exporting to EPS
should work, but PDF is far preferable.

Well, the online print shop only accepts image files (it's more a
general public site than a shop for professionals), so I would like to
do like if I were ordering my original photos.

You should check carefully in which format you deliver your photos -
CMYK is probably not the best option if you're trying to pretent to
deliver original photos - these are in RGB. Unfortunately, I don't speak
French, so I cannot check their page.

Tino.

[Fabien SK]

Hi Tino!

Post by Tino Schwarze
Well, I suppose, if they auto-correct your pre-layouted pages, things
might get pretty worse because there are multiple images in it (not so
with ordinary photos) and you've got a lot of black there. The images
might get very distorted.

I will have an idea about it, I ordered again some independent photos
with my layouts, with and without automatic correction, hoping that it
will be the same for the book printing. What's strange is that I ask
many of my friend and none of them had a "too dark" problem.

Post by Tino Schwarze
You should check carefully in which format you deliver your photos -
CMYK is probably not the best option if you're trying to pretent to
deliver original photos - these are in RGB. Unfortunately, I don't speak
French, so I cannot check their page.

That's what I think the only thing I can do (well, I did not know that
CMYK JPEG even exists!).

About the profile, they explain how to do it on this page. It may be in
french, but the screenshots of Photoshop are in english :-)
They propose to work in RGB, then to export to an image using their
profile.

http://www.photoweb.fr/atelier/atelier_photo_36.asp

For the moment, I plan to:
1) export everything to PDF with no compression
2) import from PDF to some image format, maybe PNG (hhmmmmm, this
process looks stupid, but I'm not an expert and Gregory advised me not
to export to image with Scribus)
3) convert to JPEG
4) upload images, receive book

I don't know if I should use the profile conversion at step 1 or 3...
Both make sens to me (but I'm not very skilled).

Fabien

[Tino Schwarze]

Post by Fabien SK

Post by Tino Schwarze
You should check carefully in which format you deliver your photos -
CMYK is probably not the best option if you're trying to pretent to
deliver original photos - these are in RGB. Unfortunately, I don't speak
French, so I cannot check their page.

That's what I think the only thing I can do (well, I did not know that
CMYK JPEG even exists!).
About the profile, they explain how to do it on this page. It may be in
french, but the screenshots of Photoshop are in english :-)
They propose to work in RGB, then to export to an image using their
profile.
http://www.photoweb.fr/atelier/atelier_photo_36.asp
1) export everything to PDF with no compression
2) import from PDF to some image format, maybe PNG (hhmmmmm, this
process looks stupid, but I'm not an expert and Gregory advised me not
to export to image with Scribus)
3) convert to JPEG
4) upload images, receive book
I don't know if I should use the profile conversion at step 1 or 3...
Both make sens to me (but I'm not very skilled).

Looking at the profile they provided, you shoud NOT export to CMYK. They
use an RGB profile. Looking at the page, I'd suggest the following:

1) work in Scribus using RGB colors with no profile (this should be
equivalent to working in sRGB profile or whatever your camera uses - do
you have a profile for your camera?)
2) export to "Screen" PDF (not "Printer" since that will create CMYK!)
you may use lossless compression at medium level to save some disk space

3) run through Ghostscript, export to tiff24nc, like this:
gsc -dNOPAUSE -dBATCH -sDEVICE=tiff24nc -sOutputFile=image-%03d.tif \
-rRESOLUTION -dGraphicsAlphaBits=4 -dTextAlphaBits=4 -dUseCropBox your.pdf
-> replace RESOLUTION by the DPI they want
-> generates image-001.tif, image-002.tif etc.
4) run resulting TIFFs through tifficc like this:
for f in image-*.tif ; do
tifficc -i /usr/share/color/icc/sRGB.icc -o ~/Photoweb.icc -b -t0 -c2 $f ${f/image-/page-}
done

If you've got a profile for your camera, use that as input profile for
tifficc's -i option.

5) Convert to JPEG like this:
for f in page-*.tif ; do
convert "$f" -quality 95 "${f/.tif/.jpg}"
done

HTH,

Tino.

[Fabien SK]

Post by Tino Schwarze
Looking at the profile they provided, you shoud NOT export to CMYK. They

Thank you a lot for your long and useful answer (sorry for making such a
short answer, but I don't think there is much more to say). I will try
that.

Fabien

[Fabien SK]

Post by Tino Schwarze
Looking at the profile they provided, you shoud NOT export to CMYK. They
[...]

I received my test prints from the shop, and the photos with the
automatic correction are really fine, even for the prints with multiple
photos (and black background). So I will play it safe and use it, I
don't think I could get significantly better result if I do the process
with the profile.
But again, thank you a lot for all your help, for spending time on my
problem. Even if I don't use your solution I learnt many things about
the profiles, ghostscript and ?tifficc.

Cheers,
Fabien