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Lost in CMYK conversion

Started by schen, August 25, 2007, 08:20:31 AM

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In the other thread, a question was asked about the problems from switching back and forth from RGB to CMYK.  I did not know the answer so I decided to find out myself.

I took a portrait with nice skin tone and went through 10 iterations of converting to CMYK and back to RGB.  As you may see below, the picture is gradually posterized.


Pass 1

Pass 2

Pass 3

Pass 4

Pass 5

Pass 6

Pass 7

Pass 8

Pass 9

Pass 10

Shujen Chen
Windows 10, Photoshop CS6


Yes, the photo WILL degrade when switching modes. I always make a dupe of the image I'm working on and change modes on that. Then if I find a usable channel, I select all, copy/paste onto my working image.

Also, jpg's will degrade over time. I always change these images to psd first thing.
Photoshop 2021, MacPro


Now, that was interesting!!  I just love learning.  Thank you for sharing.



Many thanks for this valuable info on using the CMYK channels, learned a lot today!   :up2:

Hannie Scheltema
Distribution Coordinator
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Thanks for posting the pictures; it was interesting to see how it degraded with each change
"carpe diem"

Margie Hayes
OPR President
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Mmmm now that was interesting...I always do the same as Kiska...only when I have finished with the final image do I then save as jpeg to reupload...

paintshop pro X1


 I think the main problems may arise when changing modes with multiple layers, PS always wants to flatten the image before changing mode, warning that you may get unexpected results with layers.

I haven't had any problems, though I usually troll through all the modes right at the start, and if I find a usable channel, like Kiska, I past it into the working RGB file. If I am recolouring an image I often change to CMYK to work, I find I seem to get better results using curves in CMYK than RGB for colouration, then again I usually leave the PSD file CMYK and flatten the image at the finish and convert that back to RGB and then Jpg.

Wisdom is having a well considered opinion .... and being smart enough to keep it to yourself!     MJS

"Life" is what happens while you are planning other things!