CMYK Color Shifts... Why?

[Bruce Kieffer]

I created a custom color with a CMYK of 7-7-30-9. Vectorworks changes that to 14-11-30-0. Why is this? How do I get the color to stay as what I enter?

[michaelk]

Interesting.

I just tried it. My machine changed your color to 15,11,33,0.

michaelk

[propstuff]

A very reliable source said that the Apple colour picker does/can not use CMYK values.

So whenever you enter a CMYK value the OS turns it into the nearest RGB it feels like.

I.E you can't actually use CMYK colours with any program which employs the Apple OS colour picker

How's that for unexpectedly crapulous?

[Bruce Kieffer]

I have no reason to doubt you propstuff, and I will call Nemetschek today and ask them this, but then why does VW allow me to enter colors as CMYK if it's going to change it to something else anyway?

[IanH]

Its the last of your worries. Vectorworks does not offer colour management for printing so won't print colour calibrated anyhow. Workaround is to export as PDF then use Acrobat and colour management to a calibrated printer.

[Bruce Kieffer]

Ian,

Are you suggesting that instead I should use RGB colors in VW, and then if I need to go to print, export a PDF and change the color space to CMYK in Acrobat?

[IanH]

I'm not really sure what I am suggesting as colour space is quite tricky to manage if you are not in full control of the end to end process. I use a calibrated scanner, monitor and printer and often find myself tweaking settings depending on the type of document I am working on - it would be fair to say that I am not 100% sure what I am doing as much is by trial and error, but at least, in a calibrated environment, I can see the effects of my changes.

However, I generally take the following approach. I work in the colour space of the source unless I am manipulating colours, or the application does not support the colourspace, in which case I work in the colour space of the application - which I think in the case of VW is RGB - having had a quick play of your colours I have found that I cannot actually input CMYK colour values in 2009 under windows, so I assume its not CMYK.

Then, if I need to output in another format, I either leave it to the print/ad bureau to do the convert and send me the proof, or I convert using the highest quality conversion that I can - ie Photoshop and proof it myself, and trust that the print/ad bureaus printers are correctly calibrated.

The fact that my printer prints in CMYK is immaterial to me even if I am working in RGB, which is 95% of the time as I have calibrated it for the paper that I intend to use, so leave it to the application, my calibration software, the printer driver and OS to get it consistent.

But this does rely on the application being colour managed, which VW (at least 2009 and before) is not. If I print direct from VW, colours will differ, often by significant shades, from the calibrated approach using Acrobat with colour management.

Looking at your required colour, and the colour VW changes it to, in Photoshop I can see that the difference in shade is insignificant compared to using Vectorworks printing without colour management.

So yes, as a starting point, use RGB in VW and export to Acrobat and use colour management in acrobat when printing, if correct colour rendition is important.

[Bruce Kieffer]

Ian,

Thanks for the input. It will greatly help me.

[Bruce Kieffer]

Nemetschek tech tells me that this is a known issue. It's on the fix list. VW is suppose to handle CMYK. In the meantime, I should use RGB.

[brudgers]

Notice that both the conversions end in zero?

It looks like custom Vectorworks colors are RBG/HSV only.

Then again, you're not going to actually pick up a CYMK color from a computer screen.

You can select colors correlating to a desired output using one of the standard color pallets, such as Munsell or Pantone.

This should give you CYMK equivalents of the selected color.

In my opinion, if color fidelity of printed output is a high priority, Vectorworks is not the proper prepress application.

[propstuff]

why does VW allow me to enter colors as CMYK if it's going to change it to something else anyway?

Because it's not VW that's changing them, it's Apple's colour picker.

This apparently is one reason that Adobe uses their own colour picker and not the computer OS colour picker.

[MacG3Freak]

Try turning off Quartz imaging processing.

[Bruce Kieffer]

Try turning off Quartz imaging processing.

Tried that. No difference. I'm converting my colors to RGB and testing that way.

[brudgers]

Try turning off Quartz imaging processing.

Tried that. No difference. I'm converting my colors to RGB and testing that way.

Why not use one of the standard colors?

Sherwin Williams and Benjamin Moore will deliver a box full of color chips for free.

Edited November 12, 2009 by brudgers

[MacG3Freak]

Why not use one of the standard colors?

Sherwin Williams and Benjamin Moore will deliver a box full of color chips for free.

That's a good idea, use built in Pantone colors. Are you printing this yourself or having someone else print it? If you're printing it yourself, what software are you using to print it?

[Bruce Kieffer]

I'm creating a library of wood tones. I am red/green color blind, so I cannot rely on my eyes to get colors correct. Having a library of named colors that others helped me create is what works for me.

[MacG3Freak]

Aahhhhh, that makes sense. Hmm...well, if you have a copy of photoshop, I suggest making a cmyk photoshop file with blocks of colors that you want to use (your cmyk values) and using the eye dropper to get the pantone values.

http://www.ehow.com/how_5091235_convert-cymk-pantone.html

Then you'll have the named versions of your colors, which I imagine will make it even easier.

Edited November 12, 2009 by MacG3Freak