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Converting from RGB to CMYK makes the image dull. How do I fix?

Apr 21, 2010 1:00 PM

I have an image that has a really bright vibrant blue in it. When I convert it from RGB to CMYK, it gets pretty dull. Is there a "trick" or something to do to a file after converting to CMYK to bring back some of it's vibrancy?

 
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  • Currently Being Moderated
    Apr 21, 2010 1:06 PM   in reply to TwitchOSX

    Simple. Don't convert to CMYK and it won't look dull. 

     

    CMYK has a smaller color gamut than RGB. Google for "cmyk rgb gamut" for TMI.

     
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  • Currently Being Moderated
    Apr 21, 2010 1:22 PM   in reply to TwitchOSX

    Try various adjustment layers. Use the mask to isolate the effects.

     
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    Apr 21, 2010 3:08 PM   in reply to TwitchOSX

    First, don't waste time comparing the vibrant blue in the RGB file to the converted blue in the CMYK file; it'll just get you depressed. Do your conversion, close the RGB file and work on the CMYK file.

     

    Then, place a color sampler point in the blue area of the image. You'll see that read out in the Info Panel as "#1".

    The Info Panel readout will show you the C, M, Y, and K ink values (precentages) of that point in the image.

     

    The most vibrant blue (like a sky blue) in the CMYK color space will be 100% cyan (100C) and about 70% magenta (70M). Any amount of the contaminating colors (in this case, yellow and black) will reduce the vibrancy. Yellow will "dirty" it up, and black will darken it. Of course, a lighter blue will have over-all lower ink percentages. The goal in making blue more vibrant is to reduce the level of the contaminating color(s).

     

    There are many ways to manipulate a color in a CMYK file.

    An easy way is to add a Selective Color adjustment layer which allows you to add or subtract ink from a specific color.

     

    Open the Selective Color panel.

    Click on the Colors pop-up and choose Blues.

    At the bottom of the panel, click the Absolute radio button.

    While looking at the #1 readout on the Info Panel, use the sliders to reduce the contaminating color(s).

    You should see the effect change on screen in real time.

    Note: you'll not remove ALL of the contaminating colors; the goal is to reduce them.

     

    This is the VERY short version of what can be a VERY long story. But it should get you started.

     

    HTH,

    Rick

     

    _________________________________

     

    Rick McCleary

    author, CMYK 2.0: A Cooperative Workflow for Photographers, Designers, and Printers

    Peachpit Press

     
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  • Currently Being Moderated
    Apr 21, 2010 3:53 PM   in reply to Rick McCleary

    You can make it a bit better using again the adjustment layers

    and selection Hue/Saturation where yo can concentrate on the saturation and color shift

    without worrying about contrast and brightness.

     

    No matter how adjust it do not expect to see this same result on the printed piece it will be duller.

     
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  • Currently Being Moderated
    Apr 21, 2010 4:19 PM   in reply to Wade_Zimmerman

    Wade_Zimmerman wrote:

     

    You can make it a bit better using again the adjustment layers

    and selection Hue/Saturation where yo can concentrate on the saturation and color shift

    without worrying about contrast and brightness.

    ... or use a Selective Color adjustment layer with blend mode set to Color.

     

    The short story gets longer!

     

    _________________________________

     

    Rick McCleary

    author, CMYK 2.0: A Cooperative Workflow for Photographers, Designers, and Printers

    Peachpit Press

     
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  • Currently Being Moderated
    Apr 21, 2010 8:18 PM   in reply to TwitchOSX

    ...or make sure there is something of contrasting color in your image - say a bright yellow or orange - and emphasize that as well as the Selective color moves Rick has suggested. Having a contrasting color will make the blue seem bluer than it really is, tricking the limited gamut of press inks into thinking they're more colorful.

     
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  • Currently Being Moderated
    Apr 21, 2010 8:27 PM   in reply to p_d_f

    well said, p_d_f.

     

    What p_d_f is talking about is not really CMYK file prep, but basic color theory. Study the Sistine Chapel, Leonardo, or any of the great Renaissance painters.

     
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  • Currently Being Moderated
    Apr 21, 2010 10:16 PM   in reply to TwitchOSX

    If you know you'll need to be dealing with CMYK on a regular basis, it's well worth picking up Rick's book, CMYK 2.0. I happened upon it while browsing the stacks at the bookstore and it's a total keeper.

     

    Heck, even if you'll only be dealing with CMYK on an occasional basis, it's probably still worth it.

     

    Unlike a lot of previous tomes about working with four-color, it's both very pragmatic and written from a photographer's perspective.

     

     

    End unsolicited, uncompensated sales pitch.

     
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  • Currently Being Moderated
    Apr 22, 2010 6:01 AM   in reply to TwitchOSX

    If there is a chance that an image will be reproduced in various CMYK-spaces (say, printed as a poster on a sheet fed press but also in magazines or newspapers) it might be beneficial to maintain the RGB-file and color correct there (with the proper View – Proof Setup/s), then separate from that file according to the various requirements.

    Correcting the resulting CMYK-files may naturally still improve the results, though.

     

    As you seem not very familiar with CMYK there’s still the question if the CMYK-profile you use for separating is actually the appropriate one for the specific purpose. If in doubt better ask the print-service-provider.

     
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  • Currently Being Moderated
    Apr 26, 2010 3:16 PM   in reply to TwitchOSX

    Hello, I just happened upon this discussion after trying to solve the same issue with a brochure I am sending to UPrint.  The initial proof was disappointing to say the least.  I have spent the weekend trying to educate myself on color-management--oh my goodness!  But your suggestions here have already helped make a difference with the first converted CMYK image I am working on--so THANK YOU!

     

    Question on workflow... so do I convert my sRGB to CMYK, work to fix different color issues using some of the methods above, then what?  Where does the printer's profile come into play during all of this?  UPrint told me for offset printing they use US Web-coated SWOP v.2.  Just not sure what to do with this information--I guess it's used in soft proofing but sure how all this works.  If I soft proof and it's still not looking right, am I able to edit with their profile turned on some how? 

     

    Also, should I get a profile for the paper I'm  using as well? --Although I've read somewhere it's hard to have your monitor replicate paper because monitors are so bright....

     

    Oh, thought I'd add a tip to this discussion which might be sort of a "no-duh--well that's obvious" tip to those of you who are able to answer all these questions, but might help those who are new to all of this...  When you're still in RGB but you want to see what colors are going to be "out of gamut" once you've converted to CMYK, click  Control+Shift+Y (also found under View> Gamut Warning).   It's very handy in knowing where to focus your attention once you've converted to CMYK.

     

    Thanks again for the great info in this forum!

     
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  • Currently Being Moderated
    Apr 26, 2010 3:46 PM   in reply to Sharingene

    So glad that you recognised the need for colour management, we get so many new visitors that come here and think we are all nuts just trying to sell colour management or something and that we just like putting down newbies...

     

    You will use the printer's profile as the destination for your 'export to PDF' routine.  If you are not making a PDF, you can use the printer's profile for soft-proofing but it rarely helps unless you have a very special job but even then you will usually get a hard proof anyway which is much better than any screen proof.

     
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  • Currently Being Moderated
    Apr 26, 2010 5:45 PM   in reply to Sharingene

    Sharingene wrote:

     

    Question on workflow... so do I convert my sRGB to CMYK, work to fix different color issues using some of the methods above, then what?  Where does the printer's profile come into play during all of this?  UPrint told me for offset printing they use US Web-coated SWOP v.2.  Just not sure what to do with this information

    Whenever you convert, you're always converting from the source color space to the destination color space.

     

    In this case, your source color space is sRGB, because that's the color space your file is in.

    Your printer told you that the CMYK profile they use is USWebCoatedSWOPv2, so that's the destination color space you want to convert to. You can consider that the printer's profile.

     

    So, how to convert?

    There are two ways.

     

    First, you could go to Image > Mode > CMYK. Easy, but maybe not right.

    That method will convert to whatever defaults are set in Photoshop's Color Settings (Edit > Color Settings). Check out your Color Settings. If they are set to any of the North America presets, you're in good shape, because the CMYK default is USWebCoatedSWOPv2. However, let's say that the printer told you to use Web Coated SWOP 2006 Grade 3. Then you need to take a different approach...

     

    Second way: go to Edit > Convert to Profile...

    In the dialog that appears, click on the Destination pop-up and scroll to find the appropriate profile.

    Click OK. Conversion done.

    This is a more deliberate method that also gives you control over Rendering Intent. (That's another discussion. For now, use Relative.)

     

    -I guess it's used in soft proofing but sure how all this works.  If I soft proof and it's still not looking right, am I able to edit with their profile turned on some how?

     

    A soft proof is an on-screen simulation of what your color will look like once you do the conversion. In your case, you would turn on soft-proof (command-Y) while still in sRGB to simulate the look of the CMYK color space.

    To select the color space to simulate, go to View > Proof Setup.

    Click on Custom...

    Click on the Device to Simulate popup.

    Scroll to find the destination color space.

    Then when you hit command-Y, you'll see a soft proof of that color space.

    Best practices suggest that you do the bulk of your color correction while still in RGB, but with soft proof on.

     

    Also, should I get a profile for the paper I'm  using as well?

    That's what the printer's profile is.

     

    Although I've read somewhere it's hard to have your monitor replicate paper because monitors are so bright....

    Not exactly. The challenge in getting a visual match between monitor and proof/print is based on the fact that a monitor is emissive (i.e., it's a light source) and a print is reflective (i.e., it only reflects light that's hitting it.) However, in a proper, well controlled editing environment, it's possible to get a shockingly close match between monitor and proof/print. All the variables are controllable.

     

    The bottom line with all of this is to be able to get accurate, predictable color on press (or out of your inkjet) based on what you see on screen. It can be done; I do it every day. It just takes some study and rigorous process control.

     

    I humbly suggest that you check out my book.

    Good luck!

     

    HTH,

    Rick

    _________________________________

     

    Rick McCleary

    author, CMYK 2.0: A Cooperative Workflow for Photographers, Designers, and Printers

    Peachpit Press

     
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  • Currently Being Moderated
    Apr 26, 2010 7:51 PM   in reply to p taz

    Thanks! I'm definitely a believer that color management is something you need to understand if you want your images to look as good in print as they do on the screen (or almost as good anyway). It sounds like Rick's book is a winner--another reason I'm happy to find this post.

    Okay, so I need a little more advice for my brochure...  I changed my image to CMYK and made some changes that definitely improved its look.  I found making adjustments through a selective color adjustment layer really helped improve the area that was looking dull, and lowering the density slider on the "masks tab" in this layer also helped brighten the image.

    Okay so now the really silly question...  I saved this CMYK file and then went to look at it in another program (outside of Photoshop) and was surprised by what my converted CMYK image looks like---what was an ocean scene of blues now looks like some kind of strange glowing orange and yellow scene.  Uhm... is this what it's supposed to look like!? In Photoshop it looked great in a side-by-side comparison with my original RGB.  Originally, when I submitted my PSD file to UPrint in RGB they did the conversion of my file to CMYK, and then uploaded a proof back to me--but like I said--their conversion was less than desirable.  So I'm just checking--does CMYK not look like a normal color range outside of Photoshop, or did I make some kind of mistake?  Thanks!

     
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  • Currently Being Moderated
    Apr 26, 2010 8:04 PM   in reply to Rick McCleary

    Hi Rick,

    I just posted a second part to my question and then saw your reply.  I really appreciate your taking the time to write such a helpful response, thank you.  I also thought you might be happy to hear that after reading the above entries today, I did go check out your book on Amazon and ordered one.  I'm looking forward to getting it.  I've been reading through a ton of different things on the internet, but am looking forward to having a more comprehensive resource in printed form.

     

    I have learned so much about Photoshop and a myriad of other photography topics in the past year--it's amazing the more you learn, the more you realize how little you know!   Thanks again, I may be asking a few more questions!

     
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  • Currently Being Moderated
    Apr 26, 2010 8:51 PM   in reply to Sharingene

    Converted cmyk should look pretty close to rgb in most cases, but they do generally desaturate, so you could use the saturation adjustment too.

     

    Personally, I adjust using levels first, don't touch the cmyk levels main adjustment but look at the individual channels and learn to set the end points.  This, when done correctly, will give excellent results.  After adjusting the individual channels, come back to the main slider (combined cmyk) and adjust to suit your TIL and contrast.  The first step will remove any casts, the most agreeable part of cmyk adjustment in my world, the second step will optimise contrast and ink levels.

     

    There is a certain mathematical truth in this approach, especially when applied to entire images (no selections) as it accepts that if there is a cast to the image, it is all over, not just in one area and when corrected, the whole image benefits.  With this in mind it is possible to adjust a difficult image to near perfect even without knowing the appearance of the original subject.  I get this a lot in reproducing paintings where the original is not accessible and the supplied photo or scan is way off colour.  By using this technique, I make the numbers realistic and the appearance follows, usually ending up very close to the unseen original.

     

    The worst mistake I see in many places is people making selections of, say, a shirt that appears the wrong colour, then adjusting the shirt and then selecting the skin and doing an adjustment for that and so on... I have found that you almost never need to make a selection if you get the levels right in the first place.  It does happen but very rarely.

     
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  • Currently Being Moderated
    Apr 27, 2010 12:32 AM   in reply to p taz

    p taz wrote

     

    This is very well put and exactly matches my own experience.

     

    I usually send AdobeRGB downstream because final CMYK is often uncertain, but the point is valid in RGB as well:

     

    Adjusting endpoints per channel will kill color casts and get you surprisingly close to the original in almost all instances. I've confirmed this numerous times when seeing the original later.

     
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  • Currently Being Moderated
    Apr 27, 2010 8:38 AM   in reply to Rick McCleary

    Hi everyone,

     

    Thank you again for your suggestions!  I really appreciate your taking the time to reply.  I still have a really basic question and want to make sure I'm not doing something wrong.

     

    After working on an image and saving it in CMYK, if I go to look at this saved image in another viewer ie: View NX (Nikon) or IrfanView the colors look very different from the RGB version--sort of day-glow neon.  Is this normal?  The same image looks completely normal in Photoshop.  I am guessing my confusion about this is because there's some basic piece of information I'm missing (like maybe it has something to do with what ViewNX or IrfanView are set up to view).  But I just want to double check I haven't created some kind of monstrosity since it looks so different in these viewers.  I guess I can just send it in and see how the proof comes back, but I'd sure appreciate an education from anyone able to reply!  Thank you.

     

    Oh, one other question!  The images for my brochure were resized considerably from the original.  Is it better to work on the original sized image when making these color conversions and corrections?  Instinct tells me yes.

     
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    Apr 27, 2010 8:55 AM   in reply to Sharingene

    I would say yes as well smart approach.

     
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  • Currently Being Moderated
    Apr 28, 2010 3:44 PM   in reply to Sharingene

    Sharingene wrote:

     


    Question on workflow... so do I convert my sRGB to CMYK, work to fix different color issues using some of the methods above, then what?  Where does the printer's profile come into play during all of this?  UPrint told me for offset printing they use US Web-coated SWOP v.2.  Just not sure what to do with this information--I guess it's used in soft proofing but sure how all this works.  If I soft proof and it's still not looking right, am I able to edit with their profile turned on some how? 

    Somebody may have already mentioned, in Proof Setup select the appropriate CMYK profile. If the image is already CMYK select the profile of the image. Then enable "Simulate Paper White."

     

    When you do this the image will look flat and dull. But at least it's a more honest appearance, provided your monitor setup is correct.

     

    Monitor white point color temperature (5000K, 6500K) can affect the display of white points in images too, although in theory it shouldn't. Maybe others can offer some insight on this.

     

    Anyway, the idea behind "Simulate Paper White" for CMYK is pretty neat. The paper white is built into the ICC profile. It is expressed in Lab values.

     

    Under normal circumstances, and for file conversion purposes the paper white cannot be allowed to be a factor. After all – the CMYK can't possibly be brighter than the paper it's going on, right? So in a file conversion, the white is regarded (and should be regarded) as L100 a0 b0.

     

    But in reality the paper does have dullness and a color. To see this, fill a CMYK space with white. Now Convert to Profile. Select Lab. Absolute Colorimetric intent.

     

    The resulting Lab honors the true color of the paper. For US Web that ends up being L89 a0 b4. Dirty and a little yellow. The truth hurts.

     

    This is what's going on with "Simulate Paper White", an absolute colorimetric soft proof conversion. It's a neat trick but a lot of people don't use it because it makes an image look like CRAP.

     
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  • Currently Being Moderated
    Apr 28, 2010 3:19 PM   in reply to Sharingene

    Sharingene wrote:

     

     

     

    Oh, one other question!  The images for my brochure were resized considerably from the original.  Is it better to work on the original sized image when making these color conversions and corrections?  Instinct tells me yes.

    I would color correct in source color at original size, using adj layers and Proof Setup.

     

    If resizing and USM is desired, do that in source color too, but use SO's or copies.

     

    As others have already suggested – do not convert in Photoshop under normal circumstances. Let InDesign or Quark do the conversion to CMYK on output.

     
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