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Differences/tips in working in CMYK

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  #1  
Old 08-25-2009, 02:56 PM
mike60640 mike60640 is offline
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Question Differences/tips in working in CMYK

I'd like to talk about all the differences of working on CMYK images (versus RGB) in photoshop.

Most of my retouching work has been in RGB. On rare occasions, clients have thrown me a CMYK image to make corrections on, and i have been ok. But, I have not explored all the things i need to know if I am thrown into an all CMYK workflow. I know it's best to stay in RGB until you have to convert, but there are times when an image is already converted (and it's not recommended to go back and forth).

I know many filters are not available, which is a bummer when you need them. Can we hear from some who work on CMYK regularly what differences or tips they find in Photoshop and in general.

Thanks
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Old 08-25-2009, 06:00 PM
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Re: Differences/tips in working in CMYK

My curves layers all of a sudden go brighter when I drag them DOWN! OMG.

No, seriously, we used to retouch everything in CMYK and it's a great training. Because you don't have all the tools available in CMYK, back then it was worse, you get quite good at for instance channel swapping for color adjustments. ALso you never have to worry about wether that weird green is going to be out of gamut.

Sadly there are colors (YES I am looking at you Chelsea goalie outfit green) that you just can't get properly in CMYK, but then again, you wouldn't be able to get them in any print, so it's a good thing. I liked working in CMYK, because you have a limited ammount of options, you get creative with what you have.
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Old 08-25-2009, 06:22 PM
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Markzebra Markzebra is offline
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Re: Differences/tips in working in CMYK

I also have a background of working in CMYK. Its useful for knowing how print works, what happens to your RGB image when it hits the page, how the black ink, density is generated from the tonality of the image, and how many different ways there are to do this. Color curves work much more subtly when working on the CMY channels, and skin tones are a particular pleasure to correct this way. Does nothing that RGB can't do, but these curves are smoother to operate. I think anyone working with color would do well to correct a few images in CMYK as a learning process.
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Old 08-25-2009, 06:35 PM
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Re: Differences/tips in working in CMYK

Working in RGB is not a problem but you'll need to convert to CMYK if it is intended for Offset printing. You can always go back and forth between modes to check your colour.
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Old 08-25-2009, 06:45 PM
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Re: Differences/tips in working in CMYK

Quote:
You can always go back and forth between modes to check your colour.…
No you shouldnt - Smart Objects and Gamut Warning

Last edited by Markzebra; 08-25-2009 at 10:51 PM.
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Old 08-25-2009, 10:49 PM
edgework edgework is offline
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Re: Differences/tips in working in CMYK

The most significant difference is the fact that shadow detail is routed out of the color channels into the black plate. CYMK offers opportunities for contrast curves to bring out shadow detail that RGB has problems with. For example, a dark area in the green channel could be a shadow, but it could also be a bright red dress. It's sometimes difficult to work on shadows without messing up the color elsewhere. Often, even if I never need to leave RGB, I'll dupe the file, convert to CMYK and steal the black plate as a selection mask for working with more precision in RGB.

It's true that the color palette is reduced, but you'd be surprised at how few colors in the real world are specific to RGB. Day glow neons, a whole range of pastels, but that purity is usually aritificial. If you're working on natural shots, you usually don't lose much going into CMYK. A dress that relies on a wide variety of blue and green tones would be an exception; that can turn into mud and other tricks are called for due to the fact that cyan is a really weak ink. Skin tones are usually enhanced by moving into CMYK. It's easy to get hot red shadows and highlights in RGB, tones that are desaturated into more natural ranges in CMYK.
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Old 08-25-2009, 10:56 PM
mike60640 mike60640 is offline
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Re: Differences/tips in working in CMYK

I can see where working in CMYK for a while would be a good discipline.

I have done a couple jobs where there was a filter i desperately needed to create a texture. I simply created a duplicate image from it's current state, switched it to RGB and used the filter. Then dragged the results (layer or group of layers) back to the original CMYK image and watched it the colors were shifted or clipped (usually not to much).

Good to know I'm not crazy thinking the curves were more sensitive in CMYK. Notice any other operations are different?
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Old 08-25-2009, 11:07 PM
mike60640 mike60640 is offline
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Re: Differences/tips in working in CMYK

edgework: Thanks. Great things to know.

Flotsam: I'm assuming you mean to switch between RBG/CMYK to see how the colors may shift or clip. But not switching while doing edits between switches.
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Old 08-26-2009, 01:28 PM
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Re: Differences/tips in working in CMYK

Just make sure that you view the file in CMYK to see the correct colours.
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Old 08-26-2009, 02:14 PM
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Re: Differences/tips in working in CMYK

View - Gamut Warning, and proof colours
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