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_Aykut_Kaplan_
Participant
September 21, 2007
Question

Best results when changing RGB to CMYK

Hi There,

How can I get the best results when converting a RGB to CMYK? For example, a tif visual when offset printing... Is there any programme, plug in, machine for this?

Many thanks
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      _cliffinmi_
      Participant
      December 20, 2007
      I agree with Marco U.

      I might have said: only use Perceptual if an extremely important color in a photo changes terribly using Relative Colorimetric -- otherwise use that. The reason: The former method can make the whole picture shift (usually yellower and weaker) but the latter can make several distinctly different colors (like 3-5 different reds for example) and make them the same. Usually, one or two really strong colors can get shifted somewhat, but won't be noticeable in an otherwise great looking image.

      The secret to converting for good print color is to choose the source and target correctly.

      If you are serious about color, buy the book "Real World Color Management" by Bruce Fraser, Chris Murphy and Fred Bunting.

      http://www.amazon.com/Real-World-Color-Management-2nd/dp/0321267222/ref=pd_bbs_sr_1?ie=UTF8&s=books&qid=1198178251&sr=1-1

      Sadly, Bruce Fraser passed away, so the book may not go to a third edition.But you can still get the second edition and the first 5 or 6 chapters are an education in themselves.
        A
        Anonymous
        October 16, 2007
        To convert an RGB file to a target CMYK space, open the image file in Photoshop, then go to Edit > Convert to Profile.

        Once there, select your target profile (a copy of which should be in the [Your Computer] > Library > ColorSync > Profiles folder, or else it will not appear in the pulldown menu).

        Then select a rendering intent appropriate for your image (to simplify, Perceptual if the relevant image colors are out of the target's gamut, otherwise Relative Colorimetric). If you select Relative Colorimetric, it's also a good idea to check "Use Black Point Compensation".

        Do NOT use the Image > Mode > CMYK command to convert your image, because that does not offer the degree of control that you have with Convert to Profile, and limits you instead to the target space and conversion controls set in the application's Color Settings, which may not be appropriate for your purposes.

        There's more to all of this, of course, but that would be a good start.
          P
          pullela kartik
          Known Participant
          March 20, 2017

          Hello Macro,

          I really need this question answered in a more simplified way.

          I believe the solution/answer you provided was the right action to get the job done. But, I did not understand.

          I am not a big expert of the color subject and not a technical expert. But I am in need for this.

          I created a logo for a client in photoshop using RGB profile. Client approved the design and colors. And wanted me to provide the design in CMYK as well.

          In the past, for the same purpose in photoshop, I used to open a new file with CMYK profile and drag the logo layers from RGB file to CMYK file. And publish the file into desired formats.

          Was that a correct approach?

          Pls let me understand the best way to do the needful. Thanks.

          regards

          Kartik

          NB, colourmanagement
          Community Expert
          NB, colourmanagementCommunity Expert
          Community Expert
          January 15, 2018

          I'm replying to Stephen cause he sounds the most technical but I am desperate for help from ANYONE with this conversion.  I have created an Ad in PS15, Adobe RGB as I always have but this magazine is asking me for CMYK and 300+dpi. I followed Marco's instructions but didn't find "Convert to Profile" in Edit - anywhere, I clicked on every one of the drop-downs.  I DID find in Image "Convert Color Profile" with the only options to "Convert to sRGB" or "Convert to Adobe RGB" which I already thought I was in?!? I have to turned in on Friday (thank you Boss!) Help...please!


          HI Maurer6455


          


          This is a particular forum that doesn’t get a lot of traffic, for sure.

          For me, this is a colour management issue, rather than general photoshop, so I feel its ideal place would be the COLOR MANAGEMENT Forum here: https://forums.adobe.com/community/design_development/color_management - I’ll give you some answers here anyway.

          Don’t start again lets do it here.

          .

          Also - for a new question it’s generally good to start a new thread title.

          So, you made an ad. in Photoshop (you write "PS15"?) using the sRGB colourspace. Is that right?

          Or you’re using Photoshop Elements?

          The edit / convert to profile is definitely there in Photoshop!

          Of course you’ll need advice on what CMYK profile to convert to. Each printing method has its own idiosyncrasies and paper type affects that too (coated/ uncoated etc). Also, printing in Europe uses different CMYK standards to the USA. You MUST ask the printer.

          If all this seems a bit much, you’re right, for many it is too much responsibility - please do not make changes after guessing about CMYK profiles etc.

          You would be FAR better to hand the sRGB file to the designer or printer and ask them to

          1: make the conversion

          and

          2: make a proof so you can check appearance.

          This proof [viewed in daylight, or ideally a proof viewing lightbox] should compare pretty well to the ad you made as viewed on your (properly calibrated) screen [viewed in a darkened room].

          But some colours that can be created in sRGB cannot be printed, even on decent paper, and, as you move down the CMYK gamut [gamut = colour range] scale towards newspaper print it gets worse.

          Don’t be downhearted, though, we’ve all seen ad’s for the exotic holidays, e.g. the Caribbean in newsprint and, although they colours are muted, they still can look good if the file was set up properly.

          Photoshop has the tools for CMYK conversion, it offers various rendering intents to deal with colour repurposing during the conversion.

          In this circumstance the logical choice would be between Relative Colorimentric & Perceptual Rendering.

          The best way to learn about Relative Colorimentric versus Perceptual Rendering is to make the conversion those 2 different ways and check on your (calibrated) screen how satisfied you are with the result. Open the 2 converted files next to each other and compare and choose.

          Photoshop also offers soft proofing which allows those working in RGB to preview the effect of the final CMTK conversion whilst they are working editing the file. Great tools.

          Do you have Photoshop and you are working with Layers?

          - then here’s a tip you may find useful:

          Just FYI I suggest you flatten any layers (maybe make a copy of the RGB file first and archive the layered RGB if you feel the need, you may want to rework the file one day).

          I hope this helps 


          if so, please do mark my reply as "helpful" and if you're OK now, please mark it as "correct" below, so others who have similar issues can see the solution


          thanks

          neil barstow, colourmanagement

            LucienSchilling
            LucienSchilling
            Known Participant
            October 16, 2007
            Photoshop - Illustrator - InDesign and respect your colour profiles (sRGB <> AdobeRGB etc).

            Lucien.
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