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RGB CMYK LAB and Dan Margulis !

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  #61  
Old 02-06-2010, 06:30 AM
Quantum3 Quantum3 is offline
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Re: RGB CMYK LAB and Dan Margulis !

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Originally Posted by Markzebra View Post
Yeah you have to be very careful with LAB, its very destructive if you use it on 8 bit images and convert those straight back and forth. This process compresses the color information into a very small area of the A and B channels. One way to minimise this damage is to convert your image to 16 bit then convert to LAB, do your edits and convert back. Another point that Margulis for some reason took many years acknowledge, is that a lot of the edits achievable in LAB can be done on the original RGB or CMYK document using Blend modes and luminosity/colour calculations. Its not always necessary to damage your file by converting to a different mode.

Margulis is a great teacher, but he has never been great a technician and the folks at Abode have had a few problems over the years with this
Hey Mark, I was missing your comments. What are you doing lately?
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  #62  
Old 02-08-2010, 03:26 PM
katheo katheo is offline
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Re: RGB CMYK LAB and Dan Margulis !

Thanks mistermonday for your help. I will do the conversion back to RGB before each print. And, I will resample down to 240 and see whether I notice any difference in the printout.
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  #63  
Old 09-13-2011, 09:49 PM
jeno jeno is offline
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Re: RGB CMYK LAB and Dan Margulis !

Hi,

I am new here, after reading all your comment. I am wondering if this is what I should be looking at if i am doing color correction for print/press?

I am doing color correction and a little bit of retouching for various printing process such as flexo, offset, gravure...etc. I am working with CMYK images most of the time. Since I am new to this industrial (print & color correction), can somebody please point me to the correct direction where/how to began and go beyond that.

I have a stack of images on my desk waited for me to be color corrected (some with color target, some without color target), since I have no idea what am I doing and what I am looking at. I doubt that I won't get it done in time!

Thanks
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  #64  
Old 09-14-2011, 01:03 AM
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Crapaud Crapaud is offline
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Re: RGB CMYK LAB and Dan Margulis !

Hi, Jeno, and welcome to the forum.

Dan's book "The Classic Guide to Color Correction" is mostly aimed at correction for print and almost exclusively for litho. It's a great, but in-depth book and much of it will be beyond a newbie to PS. Generally, I'd recommend getting to know the tools and how and when to use them first, but I reckon that you'll get a lot out of the first few chapters. I'd forget what's discussed above and just work with the book from the start.

Good luck with your work.
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  #65  
Old 09-15-2011, 09:56 AM
jeno jeno is offline
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Re: RGB CMYK LAB and Dan Margulis !

Thanks Crapaud.

Is this the book you mention? "Professional Photoshop: The Classic Guide to Color Correction (5th Edition)" ?

Thanks
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  #66  
Old 09-15-2011, 10:45 AM
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Ice Imaging Ice Imaging is offline
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Re: RGB CMYK LAB and Dan Margulis !

The one struggle I've had with Dan Margulis is staying with him long enough to sort out whatever technique he is explaining. You get three pages of Dan for every one page of technique if you know what I mean. Entertaining for sure, and the techniques are usually worth it, but man do his books ever require a box of highlighters, a note pad, and a gracious attention span. :-)
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  #67  
Old 09-15-2011, 12:26 PM
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Crapaud Crapaud is offline
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Re: RGB CMYK LAB and Dan Margulis !

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Originally Posted by jeno View Post
Thanks Crapaud.

Is this the book you mention? "Professional Photoshop: The Classic Guide to Color Correction (5th Edition)" ?

Thanks
Yes, that's the one, Jeno.

Ice Image, I know what you mean, it could be tough going a lot of the time, but well worth it IMO. I've just read the blurb for the latest edition and it seems that he's addressed it along with new techniques and problems. I'm almost tempted to buy it myself as I've got the Prof Photoshop 7 edition.
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  #68  
Old 09-15-2011, 01:28 PM
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Re: RGB CMYK LAB and Dan Margulis !

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Originally Posted by Ice Imaging View Post
The one struggle I've had with Dan Margulis is staying with him long enough to sort out whatever technique he is explaining. You get three pages of Dan for every one page of technique if you know what I mean.
Boy, do I ever!
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  #69  
Old 09-16-2011, 08:26 PM
jeno jeno is offline
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Re: RGB CMYK LAB and Dan Margulis !

I was watching a presentation by GretagMacbeth and come across a term called "L*C*H*. I would assume L*A*B* that they mentioned would be the same as what have been discussed here. Does anyone know LCH is or does it covered in Dan Margulis book?

Thanks.
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  #70  
Old 09-16-2011, 09:44 PM
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mistermonday mistermonday is offline
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Re: RGB CMYK LAB and Dan Margulis !

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Originally Posted by jeno View Post
I was watching a presentation by GretagMacbeth and come across a term called "L*C*H*. I would assume L*A*B* that they mentioned would be the same as what have been discussed here. Does anyone know LCH is or does it covered in Dan Margulis book?

Thanks.
L*C*H* stands for Luminance, Chrominance, and Hue which is quite different from the L*A*B* model.
Regards, Murray
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