Recent posts

#91
Beginner Talk / Re: Color management: colors o...
Last post by a.l.e - March 12, 2023, 06:46:00 PM
hi jo

you might want to have a look at

https://en.wikipedia.org/wiki/Color_space

and more specifically to



https://en.wikipedia.org/wiki/Color_space#/media/File:CIE1931xy_gamut_comparison.svg

or



https://en.wikipedia.org/wiki/Color_space#/media/File:Colorspace.png

(the second one is more what you want, but it's not so nice...)

some colors are not common to all the RGB spaces (the screen colors) and many colors of the RGB spaces cannot be represented in CMYK (the printer colors).

ciao
a.l.e
#92
Layout Issues / 3 fold brochure
Last post by know473 - March 12, 2023, 05:53:40 PM
Hi there,

as a complete newbie to fold brochures I want to create a 3-fold roll brochure to be printed by a professional printhouse. I want to provide them with a pdf file. (The graphic designers there use Adobe software, so I want to avoid discussing the underlying source file.)

I would create a Single Page type of document with 2 pages in Scribus (my version is 1.5.7) and arrange the content in 3 panels per page as depicted in the attachment.

What I do not understand is, how to include "folding marks" of "folding guides" or however it is called (I do not know the right expression) so that the printhouse knows where to fold. I want to control their exact position as the panels may not be equal size etc.

(Maybe I should mention that I also tried the Facing Pages type of document just to see how it works in Scribus, even though there is only the half fold option with 2 panels next to each other. As a result, it exported every panel as a separate page with bleeds. I expected it would export 2 pages with 2 panels per page and bleeds around each pair of panels.)

Many thanks!
#93
Beginner Talk / Re: Color management: colors o...
Last post by J0j0 - March 12, 2023, 02:47:38 PM
Hello utnik,

Thank you so much for your reply, this was very helpful - I somehow did not realise that the colour management is intended to take care of out of gamut colours as well.

Could you please help me understand what would be considered `extreme green or blue corners of the rgb space'? I understand this as meaning that the G- and/or B-value of the RGB exceed a certain threshold (e.g. anything with G- and/or B-values above 240 on a [0,255] scale).

I checked all images in my file: colours out of gamut are indeed mainly dark colours, however, there are a few colours that are neither dark nor red tones (in HTML notation: f6ec3c, 27bcb2, 5eccf2, 45b75c and 83d4f3). If these fall into the `extreme green or blue corners of the rgb space' category, how could I deal with this - would I necessarily require colour proofing or are there alternative approaches?

It is actually hard for me to tell how important color management is for this project - I did not create the images and my screen might not display them exactly as the author intended them, so I do not insist on exact shades. However, I would like to avoid significant loss of contrast or colours that do not make sense in context, such as a green sky. Since I've run into similar colour issues with a print project before, I'm now trying to do better...

Best
- jo
#94
Bitmap Images / Re: Warning after inserting an...
Last post by vadv55 - March 12, 2023, 09:09:27 AM
I am very grateful to you for detailed answers. Now I will look for the necessary settings to manage them.
#95
Raster and Vector Graphics / Re: Errors with PDF Import - w...
Last post by AdmFubar - March 12, 2023, 07:56:52 AM
Might be... but more likely it is a pdf that isnt created to spec. Have you opened the pdf in a text and or hex editor? You can view the pdf "innards" that way and get a better idea about how they were created.
#96
Beginner Talk / Re: Color management: colors o...
Last post by utnik - March 12, 2023, 07:48:15 AM
hello jo

depending on your images, this may not be an issue at all.
the 'out of gamut' warning just tells you, that this part of the image will be adjusted to match the export profile.

for images you normally select 'perceptual' as the rendering intent. that means, the whole color range will be adjusted to the range of the output profile in a way, our eye will (more or less) just detect the reduced contrast.
for graphics it is in most cases 'relative colorimetric' – even here the full color range will be adjusted to preserve local contrasts as good as possible.
but there are at least two situations where you should deal with this 'out of gamut' warning seriously.
  • if it is not just about a darker tone, but about a color out of the extreme green or blue corners of the rgb space, which will really look different (in the red corner the difference is smaller...)
  • in cases where graphical elements need to match with parts of an image (here you have to deal with your colors and the color management in an advanced manner...)

otherwise let do the color management its job (it will take care of the ink coverage and the color conversion to the output profile...) then take a look at the exported .pdf file and decide if there is some need to adjust anything.
if your work is color sensible, you should consider a good print proof anyway. (contact your print shop.)

utnik
#97
Raster and Vector Graphics / Errors with PDF Import - what ...
Last post by adrianstephens - March 12, 2023, 07:24:59 AM
Hello all,
I've just set my first 68-page community magazine using scribus.
We have about 60 ads.  Artwork generally arrives in pdfs.
With about 20 of these,  I've had to rasterise them in Inkscape or GIMP because of import
errors with pdf.

The errors include:  mishandling of a gradient transparency over an image,  loss of
shape details,  missing line of text,  background appearing in supposedly transparent text.

I'm wondering if there is a specification for the PDF version that scribus can import, and the files I'm importing are not meeting this spec.    Otherwise a ~30% failure rate does seem surprising.

Regards,
Adrian Stephens, Cambridge UK
Former technical editor, now mostly retired
#98
Beginner Talk / Re: Color management: colors o...
Last post by J0j0 - March 11, 2023, 08:57:50 PM
Thank you for the quick response!

I tried brightening an image within Scribus with Image Effects, however, as a result, the "out of gamut" marker colour was brightened as well ... I totally did not expect this.
outOfGammut.jpg outOfGammut_bright.jpg 


I can of course edit each image in Gimp, though I'd prefer not to (does Gimp preserve the embedded colour profile? I vaguely remember having issues with creating images with non-sRGB colour profiles in Gimp before)

I also played around with rendering intent, but none of the given options resolve the out-of-gamut issue.
#99
Beginner Talk / Re: Color management: colors o...
Last post by Nermander - March 11, 2023, 08:31:14 PM
I am not very good at color management, but I have read a lot to try to understand it.

Out of gamut means that the color cannot be reproduced by a printer using the selected output profile.

Since you mention the darker colors, my guess is that printing these with CMYK generates more ink than 300% per pixel. If that is the case, brightening the images could maybe help.

Also maybe changing rendering intent may help. If it is a comic book, maybe you do not need to use perceptual (which is mostly useful for photos, if I understand right).
#100
Beginner Talk / Color management: colors out o...
Last post by J0j0 - March 11, 2023, 07:57:32 PM
Hello!

I'm new to Scribus and DTP and running into trouble with colours that are out of gamut in imported images. I've searched the forum for "color management" and checked the corresponding Scribus wiki page, but I couldn't find a solution to my problem.

What I'm trying to achieve is the following: I'm trying to create print version of a comic I bought digitally (private use). The comic is originally in PDF format and the images have embedded colour profiles: the output to pdfimages -list <file> reads
page   num  type   width height color comp bpc  enc interp  object ID x-ppi y-ppi size ratio
--------------------------------------------------------------------------------------------
   1     0 image    1568  2489  icc     3   8  jpeg   no       170  0   300   300  306K 2.7%
   3     1 image    1550  2437  icc     3   8  jpeg   no        13  0   300   300  592K 5.4%
   4     2 image    1550  2435  icc     3   8  image  no        17  0   300   300 2479K  22%
...
('icc' for all images)

From this file, I'm trying to create one with the ISO Coated V2 300% colour profile required by the printer. These are my settings in the "color management" tab:
colorManagementTab.jpg
As a result, all darker colours are shown as out of gamut.

I'm not trying to achieve a print that shows the colours as shown on my screen, I'm looking for a way to suitably convert the embedded colour profiles of the images to ISO Coated V2 300% (I hope I don't have a misconception here and this is possible with the information available to me). I'd much appreciate any pointers as to how to do this. (I'm on Ubuntu 22.04.1 LTS and using Scribus Version 1.5.8 )

Best
- Jo

P.S.: This is only the next step, however, the wiki page "color management" and a web search left me somewhat confused as to what PDF version to export to eventually. Any recommendations?