[scribus] White versus transparent pixels question

Mon Apr 25 12:18:27 UTC 2016

You are on the right track, but not quite there. Your paper color is the
whitest white you can get without using real white color. If you change
white to be a bit darker, you are essentially just adding more pigment on
background. Even if you choose to print on a black paper, you will again
just add more pigment on that black, thus making it more darker.

To get an idea on how it COULD work for you, take any png image and import
it into Scribus' image frame. Define two custom spot colors: ExampleColor1
and ExampleColor2 with arbitrary color values. Important is to just mark
those two as spot colors. Go back to editing object on canvas. Find out how
to add Image Effects. From there, choose Duotone effect and set it to use
your custom defined colors.

Hope this will bring you closer to what you want.

On Mon, Apr 25, 2016 at 1:44 PM, Marco <marco.brignoli at marcobaldo.ch> wrote:

> Tnx for your input, I'm happy it matches my intuitive understanding of
> how it could work.
> In my past I have been on the customer or IT side of all the problems
> related to printing, so CMYK, Pantone, ecc ecc are not new words,
> however I never had a real direct contact with this interesting world.
> I will give a try using spot colors with png images (and all related
> conversions),  so far the workaround has been changing the white color
> so that it is slightly different from the page color, then the pixels
> are in the output.
>
> Il 25. 04. 16 09:34, Vladimir Savic ha scritto:
> > Every color you want to print will add on top of another. If you print
> > yellow and lay down some blue on top of i, you'll end up with some shade
> of
> > green. You can do that as many times as you want and the result will be
> > always a step closer to a "rich" black. Normally, for acceptable
> > cost/efficiency ratio, we have CMYK (cyan+magenta+yellow+k) standard.
> Look
> > at Wikipedia for more information about it. You have hit the problem of
> > base color. It is simply assumed that underlying color is paper's white.
> > Everything is being build on top of it, quite literary.
> >
> > Of course, you are not the first having an idea of printing on top of
> some
> > other color. Therefore, printers started using white pigment for making
> > special - white - color. Note the word Special here. We will return to
> that
> > soon. If you don't specify that you want old, timed, recycled, yellowish
> > paper, printers (both the people that operate printing presses and
> desktop
> > printers) will ASSUME you want it printed on plain white paper. If you
> > don't want that to happen, you should then go to a printing press
> operator
> > and handle your "special" paper to him. But, at that moment he makes one
> > more ASSUMPTION for you and that is that you want it to be printed using
> > CMYK method. Computer programs for prepress make those two assumptions
> for
> > you too. The background on your working canvas in Scribus is white -
> > non-printabe. And the colors you use are in CMYK.
> >
> > What if you want to give printer your toothpaste, shoe polish or your
> > favourite perfume to print with that? It's possible, but you will not get
> > desired results with CMYK, of course. You have to define SPECIAL case.
> It's
> > the same with your white. In Scribus you should define specal color,
> called
> > Spot color, name it "White", and use it to fill objects with it. That's
> > already covered in detains in many other places. Part of it has been
> > documented in official documentation under Color Palettes.
> >
> > What is also very important to you here is that it seems that white
> > background of an image is being treated in two ways:
> > 1) Exactly as transparent, when put on canvas directly. There is no
> > distinction if your image has transparent background or not.
> > 2) Removing other colors underneath it, when placed on top over some
> other
> > Scribus' item. Now there is a distinction. If your image contains
> > transparent pixels, underneath objects will appear where transparent. If
> it
> > were opaque, white background of your image will expose paper color at
> that
> > places.
> >
> > In reality, white just exposes paper color.
> >
> > Hope this helps...
> >
> > On Sun, Apr 24, 2016 at 10:17 PM, Marco <marco.brignoli at marcobaldo.ch>
> > wrote:
> >
> >> I'm sorry, my answer in this phase is "I don't exactly" as I need to
> >> create a sample file to ask for some offers.
> >> What is given is the paper to be used, a colored facsimile of old time
> >> paper (rough, thick, etc ).
> >> Generically speaking any typographical device that can print in white on
> >> this support is a potential candidate for me.
> >> I'm really not a professional in this field, just the standard IT guy
> >> with some friends needing support for a no profit organization....
> >>
> >> I have been exploring the problem a little bit today, and my
> >> understanding so far is that there is somewhere in the code an "IF
> >> pixel_color = page_color THEN skip ELSE send_to_output" than cannot be
> >> bypassed. If this is true (?) I can put in the output all the colored
> >> pixels of an image by choosing as page_color a color not used in my
> >> document. I'm not sure of this, it is just my current hypothesis.
> >>
> >> Il 24. 04. 16 20:45, Vladimir Savic ha scritto:
> >>> This is actually one quite interesting question. You haven't told us
> the
> >>> most important thing and that is - how do you plan to print that
> >> material.
> >>> What equipment is involved in printing process? We have to start from
> >> there.
> >>> On Sun, Apr 24, 2016, 20:08 Marco <marco.brignoli at marcobaldo.ch>
> wrote:
> >>>
> >>>> I'm a new and really happy user of Scribus. It works like a charm
> with a
> >>>> few hours of self-learning, supported by the nice on-line
> documentation.
> >>>>
> >>>> I have just a problem I can't solve with a document containing an
> image
> >>>> having a white object on a transparent background (and some yellow
> >> text).
> >>>> As the final result of my work has to printed on not-white paper all
> the
> >>>> white pixels of this image will have to be in the output (printer or
> ps
> >>>> file).
> >>>> Currently the white pixels are discarded, I can see this in the
> preview
> >>>> of the print menu with the transparency option enabled, as the white
> >>>> pixels are shown as they would be transparent. By changing the white
> >>>> pixels to any other color this problem disappears.
> >>>> Can anyone please be so kind as telling me how I can have also the
> white
> >>>> pixels explicitly in my output? It is maybe trivial, but I could not
> >>>> find the appropriate switch....
> >>>>
> >>>> Tnx in advance for your help.
> >>>>
> >>>> Marco
> >>>>
> >>>>
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