CMYK and Spot Colors

[Bug Importer]

Inkscape should be able to manage and print spot
colors. That's the only way the program would gain
terrain in a profesional enviroment.

[dcberg (david-sipsolutions)]

Well, problem is, that svg, does only support rgb, but not
cmyk. That is why spot colors aren't quite possible to do.
But you're right, together with a pdf export working for all
obejcts this is crucial for professional use. (I'm designing
quite some flyers with inkscape -- not professional in a way
that I get money for it, but I'm still quite professional --
and those two things always bother me)
maybe it's possible to save all fills in the defs and have a
(quoted) color definition in cmyk color space along with an
rgb equivalent? This def would be read by inkscape, causing
to ignore the rgb.
Well, anyways, something like this to work around the problem.

[Mental-users (mental-users)]

I think the right way to do CYMK and possibly spot colors is
to implement support for ICC color profiles. They're part
of the SVG standard, and use would basically look something
like this:

  fill:#ff0000 icc-color(genericCYMK, 1.0, 1.0, 0.0, 0.0);

i.e. after the normal color specification, SVG permits an
icc-color() which can specify a color in an arbitrary ICC
color profile. This works pretty much anywhere in SVG that
you can specify a color.

The catch is that you can't really just say "CYMK" any more
than you can "RGB" -- there are many CYMK color profiles,
just as there are many RGB color profiles (at least for RGB,
SVG specifically specifies sRGB). I don't know what a good
real standard CYMK color profile ("genericCYMK" is just a
placeholder) would be.

We might also be able to cope with spot colors in that way,
giving each spot color its own ICC profile or something.
Not sure what the best course of action there would be.

In any case, note also that the as yet unfinalized SVG 1.2
is expected to have some additional support for CYMK and
spot colors, but I've not had time to look into the
specifics yet.

[Jon A. Cruz (jon-joncruz)]

Correcting the abbreviation

[Bug Importer (bug-importer)]

Yes, imo CMYK support is a *big must*. Whenever you exchange graphics on a
professional level, you need CMYK.

Lars

[Jon A. Cruz (jon-joncruz)]

Closed "[ 1467831 ] SVG 1.2 compliance / CMYK color model" as a dup of
this
request.

http://sourceforge.net/tracker/index.php?
func=detail&aid=1467831&group_id=93438&atid=604309

[Jon A. Cruz (jon-joncruz)]

Originator: NO

Closing other RFE as a duplicate of this one.
[ 1669132 ] Pallete
http://sourceforge.net/tracker/index.php?func=detail&aid=1669132&group_id=93438&atid=604309

[Centromedia (centromedia)]

Originator: NO

Mental you're on the wrong way: color profiles must be the latest part to
do and are needed only view/translate properly colors on different devices
(monitor/printer).
The user must select first the color mode he wants to use, and then eache
object must have their color values stored in the current color mode. You
can't store simply RGB values and then convert them in the output file.
This conversion is too relative to the user. CMYK values must be given as
absolute value, and they don't differ if you use color profile A or color
profile B !
Color profile are needed to make a conversion layer between the original
RGB/CMYK/LAB values and the output device.
An other thing again is how RGB values are converted to CMYK and
viceversa, it exists curves for this and they can be adapted also by the
user depending for the needs.

IT'S REALLY URGENT TO RESOLVE THIS PROBLEM INSTAED OF GOING AHEAD WITH
OTHER PARTS OF THE APP, BECAUSE MORE AND MORE CODE MUST THEN REWRITTEN !!!
MOST OF THE LATEST CHANGES DONE AREN'T SO IMPORTANT SUCH AS CMYK SUPPORT,
WHY LOOSE SO MANY TIME....

[Bug Importer (bug-importer)]

I personally don't see how big an advantage this would be. Colour vision
is three dimensional - might as well stick with RGB, and let Inkscape
convert to CMYK on the fly when e.g. printing. If Photoshop can do it, why
can't Inkscape? What would be useful is the ability to attach an ICC
profile to the document as a whole. That would address any issues of CMYK
colours not representable in sRGB. I personally don't see the point of
repeating the ICC profile on every single colour used, it will merely bloat
the document and usually all colours are specified relative to the same
profile.

[Centromedia (centromedia)]

Originator: NO

Detailed comments should be posted by people that understand perfectly
what we're speaking about and have a professional knowledge about
colorhandling and its principles. you simply demonstrated 1) you don't know
what CMYK stands for and why it exists 2) you even don't know nothing about
color in photoshop.

[dcberg (david-sipsolutions)]

Originator: NO

Hey Centromedia!

I totally agree with your points, but please be a little more polite.

Is there any work being done on this issue? From what I remember from the
email list, there isn't, which is really unfortunate.

[Jon A. Cruz (jon-joncruz)]

Originator: NO

There is quite a lot of working going on, but centromedia is not on target
with many assertions about proper CMYK in regards to vector graphics.

First and foremost, we have had far more people needing spot color support
(such as Pantone) than CMYK. For those, the workflow is very different.

Secondly CMYK color does not exist itself as an absolute concept. CMYK
truly only makes sense as a way to describe the color behavior of a
specific print or output device. Even the CMYK of two different printers of
the same model are usually different.

Finally, centromedia was incorrect about how CMYK should work in SVG.
Mental's comment describes exactly what needs to be done and the proper way
to do it. This has also been coordinated with other projects such as
Scribus.

[Centromedia (centromedia)]

Originator: NO

Hi Jon, obviously my intent wasn't to do an in-depth description and was
keeping myself short.
Sure spot colors are important, but even spot colors can be described with
RGB values but mostly with CMYK values. You mantioned Pantone. Did you ever
saw a real Pantone palette? you will never find a pantone palette with RGB
values, but you can find it with CMYK values, which is most used palette.
Spot colors is a way how they are managed (immagine const variable).
You said: Even the CMYK of two different printers of the same model are
usually different.

The difference are not the values, this are absolute ! the difference is
the color output between the printers and this differs by paper, ink specs
and screening differences.
The outputt differences between the real CMYK color and the color that is
printed is described in the color profile (color profile is a correction
table)
a CMYK value describes a precise color that is same all over the world.
If need I send you some detailed informations...

[Jon A. Cruz (jon-joncruz)]

Originator: NO

For further discussion, please go to either the developer mailing list or
the Jabber & IRC chat rooms. That would help communication go more
smoothly.

For the points you raise, yes I have seen real Pantone. Among other things
I've worked in an actual print shop with offset presses, etc.

I've seen Pantone palettes with RGB values many times, including soft
versions shipping with Photoshop. Also, there are many Pantone spot ink
colors that can not accurately be represented with CMYK values. CMYK or RGB
might be used to get a *preview* of the color while working, but that is
known to be simply an approximation.

And again, there is no such thing as pure CMYK. CMYK values only make
sense when tied to a specific output device. There are some "general" CMYK
profiles floating around out there, but for professional work precision is
needed. Aside from other things, the OpenICC project is one good source for
such information
http://www.freedesktop.org/wiki/OpenIcc

(Again, the mailing list or chat room are the appropriate places to
continue such a discussion on CMYK, etc.)

[grey tomorrow (gtomorrow)]

Hi - thanks for reporting this bug, I've manually migrated it to Inkscape's new bug tracker on GitLab, and closed it here.

Please feel free to file new bugs about the issues you're seeing at
https://inkscape.org/report .

Moved to: https://gitlab.com/inkscape/inbox/issues/2489
Closed by: https://gitlab.com/greytomorrow