CMYK color "mode" or color space?

[Abitconfused]

I see color modes, LAB, CMYK, or Grayscale in Photoshop but CMYK is also a color space isn't it? So, what is the difference between a color mode and a color space?

[Polar01]

Back away from the CMYK colour space as it is used for off-set printing.

Cheers: Allan

[xpatUSA]

I see color modes, LAB, CMYK, or Grayscale in Photoshop but CMYK is also a color space isn't it? So, what is the difference between a color mode and a color space?

Here's my two cts, Ed:

"color mode" is an undefined general phrase which, in this case, means whatever Adobe wants it to mean. However, on my camera, "color mode" means something completely different, e.g. "vivid", "neutral", "standard", etc. So, it might help if you think of "color mode" just as loose terminology used by Adobe to denote a class of color renditions.

On the other hand, the meaning of "color space" is defined by much of the literature and some examples are sRGB, ProPhoto, Melissa, Adobe RGB (1998), Y'CbCr, CIELAB, CIELUV, CMY . . the list goes on and on. In spite of what the Elephant in the Room might say, I would hesitate to call Grayscale a color space all it's own because it only has one dimension and color spaces have three or more.

So basically the difference between a color mode and a color space is that the former is undefined and the latter is both defined and universally understood.

HTH.

[Shadowman]

In terms of editing, how does it relate to the channel mixer? The question relates to cmyk more than the other modes; although L*a*b* is more closely related to rgb colorspace.

[pnodrog]

You can add colour model to your list...

I started to explain what I understood by all the various terms but scrubbed the idea because:

A it was starting to take to long
B I would probably confuse or mislead people with any minor (or major) misconceptions I have
C there is already such a big pool of accurate and inaccurate information on the net that I felt I should not add to it either way...

P.S. I do know when properly used the terms are not interchangeable.
P.P.S. Ted thank you. I see you have written a concise and abbreviated version of some of what I was going to bore everyone with.

[Abitconfused]

Prodrug I hope you will reconsider your treatise. There is so much to know that we cannot all get it correct. I have seen forums where some participants heap scorn on others for the least confusion. But this forum is not that way! We delight in each other's faults and praise idiosyncratic behavior!

[pnodrog]

Prodrug I hope you will reconsider your treatise. There is so much to know that we cannot all get it correct. I have seen forums where some participants heap scorn on others for the least confusion. But this forum is not that way! We delight in each other's faults and praise idiosyncratic behavior!

My doctor asks me to swallow so many pills each day she should be called "Prodrug"

Your encouraging reassurance has prompted me to add a little to what Ted wrote.

I understand Adobe's use of the term mode relates to the manner in which the software interface presents both the results and editing tools applicable to the "Model" we are working with. Be it RGB, LAB, CMYK, Greyscale etc. i.e. there is no point in displaying colour pallets when working with Greyscale.

A Colour space is a subset of a theoretical Colour Model and tend to limit the colours used to those that in practical terms can be reproduced by displays or printers. If there were no shortcomings in our technology (or visual response) and no restrictions on file sizes we could conceivably have an unrestricted single colour space definition. So mapped colour spaces (sRGB, AdobeRGB etc) simply reduce the number of colours available so that when working with 8 or 16 bits each for Red, Blue and Green gives a reasonable selection of colours that can hopefully be reproduced.

On top of all this we need to add colour managment and profiles so the RGB or CMYK etc values as defined by the colour space being used come out as expected when reproduce by various devices using different technologies - displays (CRT, LED, LCD etc), printers (Laser, dyesub, Dotmatrix, dye inks, pigments, 4 to 9 ink sets, etc)

Simple really.... I am surprised it works at all.

[Manfred M]

+1 to what both Ted and Paul have written.

Normally we tend to not use CMYK colour spaces in photography, BUT sometimes converting an RGB to CMYK can be a good way to go in editing, as we can edit the "K" (Black) channel as a standalone as when we do this only the neutral tones are changed, without impacting any of the other colours / colour relationships.

By convention, the CYMK colour space is set up somewhat opposite to what we do when we use RGB, with the dark tones lying on the right hand side of the histogram and the light tones on the left.

Just make sure to convert back to an RGB colour space when posting. Also, stay away from the ProPhoto colour space when working in CMYK as the conversions are often a bit extreme and the conversion process can introduce unwanted artifacts. Starting off in sRGB or AdobeRGB is usually a much better approach.


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