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bazj99
Participant
March 21, 2024
Answered

Missing/Mismatch Colour Profile - Best Practice

  • March 21, 2024
  • 3 replies
  • 2101 views

Hi,

 

What is the best way to approach a missing/mismatch colour profile message when opening an image in Photoshop?

 

Is it best to convert to the working space profile at the opening dialogue, or do nothing ('Leave as is' or 'use the embedded profile') at the opening dialogue and convert to working space after opening using Edit->Convert to profile.

 

Why is there a difference in colour doing it the two ways, when essentially you're asking for the same thing (to convert to the applications default working space), just at different stages?

 

Many thanks in advance.

 

Barry

    This topic has been closed for replies.
    Correct answer Stephen Marsh

    For an untagged RGB image, the best option is to not convert and initially use the working RGB. Then visually and numerically (Lab or CMYK info values) inspect the image to see if the default working space is appropriate or not. You may find that assigning another RGB has a better visual and or numerical result.

     

    https://prepression.blogspot.com/2014/06/rgb-icc-profile-roulette.html

     

    If the RGB image has an embedded ICC profile, then you should initially honour/accept this. You can then visually and numerically inspect the image to see if assigning another profile would change the appearance favourably over the tagged ICC profile in the file. You would need to ask yourself why you don't trust this "label".

     

    There is often no need to convert from the source profile to your working RGB, unless the source profile isn't a working space profile. If the source profile is a device profile such as a monitor, scanner or printer profile then it is best to convert it into a predictable, "well-behaved" working RGB space for further editing. One would generally convert from a smaller space to a larger space to avoid gamut clipping.

     

    Notice that I have not commented on CMYK mode files, as they have different considerations and are generally best not converted.

    3 replies

    B
    bazj99Author
    Participant
    March 22, 2024

    @Stephen Marsh @D Fosse 

     

    Thank you both for your replies.

     

    So if we are printing on a digital press that is running to Fogra39 standard, we should leave CMYK images with whatever they have embedded rather than converting to Fogra39. I had though that by converting to Fogra39 it would give a better representation on how it would print on a printer running to the Fogra39 standard. Is that not the case?

     

    Kind Regards,

     

    Barry

    Stephen Marsh
    Community Expert
    Stephen MarshCommunity Expert
    Community Expert
    March 22, 2024
    quote

    So if we are printing on a digital press that is running to Fogra39 standard, we should leave CMYK images with whatever they have embedded rather than converting to Fogra39


    By @bazj99

     

    Keep in mind that the bulk of my previous comments were specifically regarding RGB and that the only mention of CMYK was a single unqualified sentence.

     

    You have now qualified that this is regarding digital output. CMYK for a traditional press vs. digital press may have very different concerns than digital.

     

    The digital press may be set to *simulate* the F39/ISO Coated v2 offset press specification (not a standard), however, it will still be transformed into the final digital press colour space for the digital press "ink" and media. Therefore the original CMYK separation values will probably be transformed anyway. I doubt that many digital press workflows are configured to send through the source CMYK values without a transformation to the press/substrate profile.

     

    If the CMYK images have a F39/ISO Coated v2 ICC profile embedded in them, there should be no reason to convert as this would be a null transform if the intermediate simulation space is F39/ISO Coated v2.

     

    If the CMYK images have a different ICC profile embedded in them than F39/ISO Coated v2, there are two choices:

     

    1) Honour the CMYK values, ignore the profile

    2) Honour the ICC profile and convert the values to the simulation profile

     

    There are pros/cons to both and it is conceivable that either approach may be the correct or incorrect approach for any given image.

     

    quote

    I had though that by converting to Fogra39 it would give a better representation on how it would print on a printer running to the Fogra39 standard. Is that not the case?


    By @bazj99

     

    If the CMYK images have a different ICC profile embedded in them than F39/ISO Coated v2 does it mean that the file's CMYK values are incorrect and the profile is correct? Or could it be that the file's CMYK values are correct and the ICC profile is incorrect? 

     

    As long as you make it clear to customers who submit files what will happen, they can't complain that they didn't know that your chosen course of action might lead to unexpected or incorrect reproduction of their intent.

      B
      bazj99Author
      Participant
      March 25, 2024

      Hi Stephen,

       

      Do you know why there is a difference in colour when converting at the opening dialogue compared to leaving at that stage and converting using the Edit -> Convert menu.

       

      Thanks

      D Fosse
      Community Expert
      D FosseCommunity Expert
      Community Expert
      March 21, 2024

      My standard advice is to disable the "mismatch" warning permanently. There is absolutely no reason why the embedded profile needs to match the working space. 

       

      The working space is just a fallback default if there is no embedded profile. If there is, which there always should be, it will override the working space. In other words, the working space is not important, and the message tells you nothing useful.

       

      Photoshop's default policy is to "preserve embedded profiles". Don't change that. This is how Photoshop is supposed to work. That you even have the two other options, "off" and "convert to working", is mainly a leftover from back when color management wasn't widely supported. Today, those two options just cause problems, and if Photoshop was written today, it would probably be hard-wired to "preserve embedded" - like e.g. Lightroom Classic is.

       

      In short - if the image has an embedded profile, use that, unless it's a very non-standard profile that may cause problems later on. Then you convert to the closest standard profile. Standard document profiles are sRGB, Adobe RGB and ProPhoto RGB. Lately, Display P3/Image P3 is increasingly used in the Mac community, although it is basically a display profile and so that practice is a little questionable.

        Stephen Marsh
        Community Expert
        Stephen MarshCommunity ExpertCorrect answer
        Community Expert
        March 21, 2024

        For an untagged RGB image, the best option is to not convert and initially use the working RGB. Then visually and numerically (Lab or CMYK info values) inspect the image to see if the default working space is appropriate or not. You may find that assigning another RGB has a better visual and or numerical result.

         

        https://prepression.blogspot.com/2014/06/rgb-icc-profile-roulette.html

         

        If the RGB image has an embedded ICC profile, then you should initially honour/accept this. You can then visually and numerically inspect the image to see if assigning another profile would change the appearance favourably over the tagged ICC profile in the file. You would need to ask yourself why you don't trust this "label".

         

        There is often no need to convert from the source profile to your working RGB, unless the source profile isn't a working space profile. If the source profile is a device profile such as a monitor, scanner or printer profile then it is best to convert it into a predictable, "well-behaved" working RGB space for further editing. One would generally convert from a smaller space to a larger space to avoid gamut clipping.

         

        Notice that I have not commented on CMYK mode files, as they have different considerations and are generally best not converted.

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