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RGB CMYK LAB and Dan Margulis !

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  #41  
Old 11-16-2007, 09:34 AM
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Hello_taipan Hello_taipan is offline
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Re: RGB CMYK LAB and Dan Margulis !

Markzebra is God.
thx for the tip man !
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  #42  
Old 11-16-2007, 10:21 AM
pixelzombie pixelzombie is offline
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Re: RGB CMYK LAB and Dan Margulis !

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Originally Posted by KR1156 View Post
i'm in RGB 95% of time, and don't do the cmyk conversions, so i really love the bringing in the K plate. that's where i get most use out of it.

i'm trying to figure this out but can't seem to get a handle on it, how would i use the smart object to add K only to a RGB file?

Last edited by pixelzombie; 11-16-2007 at 10:22 AM. Reason: spelling
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  #43  
Old 11-16-2007, 10:51 AM
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Re: RGB CMYK LAB and Dan Margulis !

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Originally Posted by pixelzombie View Post
i'm trying to figure this out but can't seem to get a handle on it, how would i use the smart object to add K only to a RGB file?
You convert the smart object to CMYK and adjust with curves.

Chris
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  #44  
Old 11-16-2007, 10:52 AM
mr.aj mr.aj is offline
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Re: RGB CMYK LAB and Dan Margulis !

Tai,

Thanks for starting this thread...I learned a ton
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  #45  
Old 11-16-2007, 11:27 AM
pixelzombie pixelzombie is offline
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Re: RGB CMYK LAB and Dan Margulis !

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Originally Posted by cricket1961 View Post
You convert the smart object to CMYK and adjust with curves.

Chris
ok, i got that far but i can get a similar result by just using selective color on the RGB file itself...
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  #46  
Old 11-16-2007, 12:08 PM
KR1156 KR1156 is offline
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Re: RGB CMYK LAB and Dan Margulis !

Quote:
Originally Posted by pixelzombie View Post
i'm trying to figure this out but can't seem to get a handle on it, how would i use the smart object to add K only to a RGB file?

what i do is double click on the base layer of the CMYK smart object and turn all chanels off except the K, then save. when i get back in RGB, i do the necessary blending of that K plate.
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  #47  
Old 11-16-2007, 12:50 PM
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Re: RGB CMYK LAB and Dan Margulis !

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Originally Posted by pixelzombie View Post
ok, i got that far but i can get a similar result by just using selective color on the RGB file itself...
True, but you are not pushing in just black. You are pushing in an interpretation of black. At least you can dial in exactly the amount of black you want.
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  #48  
Old 11-16-2007, 01:47 PM
pixelzombie pixelzombie is offline
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Re: RGB CMYK LAB and Dan Margulis !

i'm not sure what you mean by interpretation as i'm getting the same numbers when i read the cmyk values...
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  #49  
Old 11-16-2007, 03:42 PM
edgework edgework is offline
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Re: RGB CMYK LAB and Dan Margulis !

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Originally Posted by pixelzombie View Post
i'm not sure what you mean by interpretation as i'm getting the same numbers when i read the cmyk values...
Those are the numbers you'd get if you converted your RGB file to CMYK. But as long as it's an RGB file, your shadow detail is blended throughout the three color channels. The difference is that when you manipulate a K curve in CMYK you are dealing with only shadow information in a way that RGB and LAB cannot match. I've used the K plate as a layer mask to refine my shadow moves in RGB, but it's not quite the same. That's why Dan always says that CMYK is the best space to work with shadow detail. And nothing beats the effect of sharpening the K plate only, not possible in RGB.
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  #50  
Old 11-16-2007, 03:48 PM
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Markzebra Markzebra is offline
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Re: RGB CMYK LAB and Dan Margulis !

i'm not sure what you mean by interpretation as i'm getting the same numbers when i read the cmyk values... - This is a useful technique - what Chris means by interpretation is a re-separation of the K channel back into RGB. Its the same as if you had duplicated your RGB document, converted the duplicate to CMYK, copied the K channel, and pasted this copy from the clipboard back into your original RGB document. If you now look at your three RGB channels you will see the K channel dropped into the R, G and B in equal amounts - because photoshop has made your copy into a new desaturated layer. Each of these channels is identical to the K channel in CMYK.

Glad everyone finds this stuff interesting and useful, Smart objects after the release of CS2 took me a year or so too for me to get my head around, because they were so new. But they are a pretty important usability breakthrough I think
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