CMYK vs RGB RE: PDF query

[Heiko Haida]

Hi Jacob, 

my point here is:
The CMYK option in FM is not something like a fancy gadget (that is how
I understood what Craig said earlier), but essential for a correct
colour representation in certain constellations. 

Here is an example, I enclose a screenshot: 2 rectangular objects are
visible, with colours defined as CMYK = 100/70/0/0 and 100/0/20/20. 

To the left, that is the (correct) representation in Illustrator. To the
right, thats what it looks like in FrameMaker (obviously not "correct").
In the middle that is the PDF output with the CMYK option not activated
(which is the standard - and only possible - behaviour of all older FM
version up to FM 10). 

With the CMYK option activated on the other hand, the PDF output would
in fact look exactly like in Illustrator.
And if this PDF is converted afterwards to RGB via Acrobat preflight,
the colours would still be perfect on screen. 

If you know a better or easier way or working settings for FM or
Acrobat, please tell me. 

Best regards - Tino H. Haida, Berlin 

Jacob Schäffer: 

> It's definitely NOT easy to explain this. Color conversions are COMPLEX. Anyway, RGB -> CMYK conversion is lossy, and CMYK -> RGB is also lossy. 
> 
> What is the point of the RGB switch afterall? Why not just pass through what's input and remove this switch? 
> 
> Best regards / Med venlig hilsen 
> 
> Jacob Schäffer | Chief Developer 
> 
> -------------------------
> 
> Grafikhuset (House of Graphics)
> Paradis Allé 22, Ramløse
> DK-3200 Helsinge, Denmark 
> 
> Mobile: +45 2021 1958
> Phone: +45 4848 0096
> Email: js at grafikhuset.dk
> Web: http://design.grafikhuset.dk [1] 
> 
> FROM: framers-bounces at lists.frameusers.com [mailto:framers-bounces at lists.frameusers.com] ON BEHALF OF Heiko Haida
> SENT: 20. oktober 2014 16:22
> TO: Craig Ede
> CC: framers
> SUBJECT: RE: CMYK vs RGB RE: PDF query 
> 
> Well, Craig, 
> 
> thats easy to explain: 
> When I use Illustrator or Indesign, a colour will not change its screen representation if I switch from CMYK definition to RGB definition. That is not a miracle or a question of "who knows" (these programs use HSB definitions, and obviously the conversion works very well).
> With FrameMaker, on the other hand, a CMYK colour will not look "right" neither on screen nor in the resulting PDF. 
> And only with the CMYK print option activated that has been implemented successfully with FM 10, this colour information will be transfered to the PDF correctly. 
> 
> Best regards - Tino H. Haida, Berlin 
> 
> Craig Ede: 
> 
>> Given the theoretical differences I'm not sure why you would expect RGB output of CMYK colors to be close to what CMYK color should looks like. 
>> 
>> Think of it this way, if you choose a Pantone color as a spot color, you'd expect it to print exactly like as that Pantone color to paper. But to the screen, who knows? It's be "close" but depends on the color correctness of the particular monitor.
>> 
>> Craig
 

Links:
------
[1] http://design.grafikhuset.dk/
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