Hi folks,

Does anyone know of an application that will convert RGB values to CMYK
and/or vice-versa?

It can be done using on-line converters but I can't find a stand alone
prog.

Either RiscOS or the dark Side would be acceptable.

Regards,

--
Chris

On 2 Apr 2024 as I do recall,
Chris Newman wrote:

> Hi folks,
>
> Does anyone know of an application that will convert RGB values to CMYK
> and/or vice-versa?
>
Can't you just use Paint?

The colour picker allows you to switch between RGB, CMYK and HSV values
and translates the current setting as you do so: for example 'desktop
blue' is 60% cyan, 33.3% magenta, 0% yellow and 40% black, or 0% Red,
26.6% green and 60% blue. Wind up the green and red and reduce the blue
ands you get a yellow that is 100% red, 87.5% green and 12.8% blue...
which Paint tells me is equivalent to 0% cyan, 12.5% magenta, 87.1%
yellow and 0% black.

--
Harriet Bazley == Loyaulte me lie ==

We will release no software before its time.

On 2 Apr, Harriet Bazley wrote in message
<6d006c4b5b.harriet@bazleyfamily.co.uk>:

> The colour picker allows you to switch between RGB, CMYK and HSV values
> and translates the current setting as you do so

If you want a stand-alone version, Rosemary Miskin's ColDef2 would probably
do the trick.

https://miskin.orpheusweb.co.uk/net/main2.html

--
Steve Fryatt - Leeds, England

http://www.stevefryatt.org.uk/

In article <mpro.sbc3nn00njemc05cj.news@stevefryatt.org.uk>, Steve Fryatt
<news@stevefryatt.org.uk> wrote:
> On 2 Apr, Harriet Bazley wrote in message
> <6d006c4b5b.harriet@bazleyfamily.co.uk>:

> > The colour picker allows you to switch between RGB, CMYK and HSV
> > values and translates the current setting as you do so

> If you want a stand-alone version, Rosemary Miskin's ColDef2 would
> probably do the trick.

> https://miskin.orpheusweb.co.uk/net/main2.html

That leads me to version 1.26 (2006). I discovered sitting n my machine
I already have 1.30 (2023). From whence that cometh I know not.

I was trying to help the mem sahib who was using MS Publisher.
she had concocted a yellow which according to her m/c had the values
R 255 G 252 B 0

Putting that into an online converter gave C 0 M 1 Y 80 K 0

Another converter gave the CMYK in percentages ie

C 0 M 1.18 Y 100 B 0

Putting that into paint gave percentages.
R 100 G 98.8 B 20
Tried again and got R 94.9 G 93.7 B 14.9

ColDef2 gave R 87.1 G 85.9 B 7

So something is being lost in the translation.

Now I am completely confused by the methods used to state the parameters
and the differences in translation.

I am a bear of little brain (said Pooh)

--
Chris

In article <5b4b7e44b0mec@npost.uk>, Chris Newman <mec@npost.uk>
wrote:
> In article <mpro.sbc3nn00njemc05cj.news@stevefryatt.org.uk>, Steve
> Fryatt <news@stevefryatt.org.uk> wrote:
> > On 2 Apr, Harriet Bazley wrote in message
> > <6d006c4b5b.harriet@bazleyfamily.co.uk>:

> > If you want a stand-alone version, Rosemary Miskin's ColDef2 would
> > probably do the trick.

> > https://miskin.orpheusweb.co.uk/net/main2.html

> That leads me to version 1.26 (2006). I discovered sitting n my
> machine I already have 1.30 (2023). From whence that cometh I know
> not.

I made some changes to it, but was unable to contact Rosemary for her
to accept and put on her website. So as a temporary measure v1.30 is
available from my website www.avisoft.f9.co.uk
The changes were...

- Changed Wimp_Poll to PollIdle to reduce CPU usage.
- Added test for Titanium rgb <> gbr swap to correct colours.
- Added &rgb option for colours as in Icon validation strings.
- Stopped loops in FNwimperror.
- Updated Program Information version from program.

If anyone has a contact for Rosemary, please let me know.

However, I do not think it will be useful for CMYK colours!

Martin

--
Martin Avison
Note that unfortunately this email address will become invalid
without notice if (when) any spam is received.

Chris Newman <mec@npost.uk> wrote:

> In article <mpro.sbc3nn00njemc05cj.news@stevefryatt.org.uk>, Steve Fryatt
> <news@stevefryatt.org.uk> wrote:
> > On 2 Apr, Harriet Bazley wrote in message
> > <6d006c4b5b.harriet@bazleyfamily.co.uk>:
>
> > > The colour picker allows you to switch between RGB, CMYK and HSV
> > > values and translates the current setting as you do so
>
> > If you want a stand-alone version, Rosemary Miskin's ColDef2 would
> > probably do the trick.
>
> > https://miskin.orpheusweb.co.uk/net/main2.html
>
> That leads me to version 1.26 (2006). I discovered sitting n my machine I
> already have 1.30 (2023). From whence that cometh I know not.
>
> I was trying to help the mem sahib who was using MS Publisher. she had
> concocted a yellow which according to her m/c had the values R 255 G 252 B
> 0
>
> Putting that into an online converter gave C 0 M 1 Y 80 K 0
>
> Another converter gave the CMYK in percentages ie
>
> C 0 M 1.18 Y 100 B 0
>
> Putting that into paint gave percentages.
>
> R 100 G 98.8 B 20 Tried again and got R 94.9 G 93.7 B 14.9
>
> ColDef2 gave R 87.1 G 85.9 B 7
>
> So something is being lost in the translation.

Yes, that is unavoidable. There are many ways of converting both ways and
you cannot generally expect a round-trip to get you back to where you
started from, nor can you expect that a colour in one colour space even has
a matching colour in the other.

The way an RGB colour looks depends on your monitor and its settings and the
way a CMYK colour looks depends on the ink and paper used for printing. To
get an accurate conversion, you need a process called colour management
involving a calibrated monitor and colour profiles.

The RGB<->CMYK conversion done by the RISC OS colour picker is extremely
simplistic and not really usable for defining colours for professional print
work. Some applications, e.g., OvationPro and ArtWorks (with CMYK ink
simulation switched on) do slightly better, but this is still very far from
even the beginnings of a colour managed workflow.

In the absence of a fully colour managed workflow your best bet is to go to
the printers and look at printed samples of standard colour palettes, e.g.,
Pantone and choose one of these colours. If you then put the CMYK values
given for the chosen colour into an application that can deal with CMYK
colours and you have an output process that gets them to the printers
without them being converted back to RGB on the way, then you have a chance
that the correct colour will eventually appear in the printed output.

--
Martin Wuerthner MW Software http://www.mw-software.com/

------- RISC OS Software for Design, Printing and Publishing --------

In article <mpro.sbew5n005cgba2axc.spamtrap@mw-software.com>, Martin
Wuerthner <spamtrap@mw-software.com> wrote:

<Snip>
> >
> > So something is being lost in the translation.

> Yes, that is unavoidable. There are many ways of converting both ways
> and you cannot generally expect a round-trip to get you back to where
> you started from, nor can you expect that a colour in one colour space
> even has a matching colour in the other.

> The way an RGB colour looks depends on your monitor and its settings
> and the way a CMYK colour looks depends on the ink and paper used for
> printing. To get an accurate conversion, you need a process called
> colour management involving a calibrated monitor and colour profiles.

> The RGB<->CMYK conversion done by the RISC OS colour picker is
> extremely simplistic and not really usable for defining colours for
> professional print work. Some applications, e.g., OvationPro and
> ArtWorks (with CMYK ink simulation switched on) do slightly better, but
> this is still very far from even the beginnings of a colour managed
> workflow.

> In the absence of a fully colour managed workflow your best bet is to
> go to the printers and look at printed samples of standard colour
> palettes, e.g., Pantone and choose one of these colours. If you then
> put the CMYK values given for the chosen colour into an application
> that can deal with CMYK colours and you have an output process that
> gets them to the printers without them being converted back to RGB on
> the way, then you have a chance that the correct colour will eventually
> appear in the printed output.

Thanks, Martin. That's really enlightening.

--
Chris