Skip to main content
T
Test Screen Name
Legend
October 23, 2017
Question

Re: Conversion both ways CMYK<-->RGB and color profiles

  • October 23, 2017
  • 3 replies
  • 266 views

There are no formula for ICC profiles. Each profile contains up to six lookup tables, entirely specific to the profile (and rendering intent). They are usually derived from measurements with colour reading equipment and don't follow any other rules.

    This topic has been closed for replies.

    3 replies

    D Fosse
    Community Expert
    D FosseCommunity Expert
    Community Expert
    August 28, 2020

    This looks like it has been branched/moved from somewhere else. For what reason is entirely unclear, and I suggest it is moved back to where it came from.

    T
    Test Screen NameAuthor
    Legend
    August 28, 2020

    Certainly, the first post in the thread as it currently stands "There are no formula for ICC profiles. " was a reply, not a question! I think this may be the original: https://community.adobe.com/t5/illustrator/conversion-both-ways-cmyk-lt-gt-rgb-and-color-profiles/td-p/9465382?page=2  The first reply there begins "Hmmmm, and I am guessing there is no simple viewer for those lookup tables?" which seems to be a reply to my reply, now separate and here.

    TheDigitalDog
    TheDigitalDog
    Inspiring
    August 27, 2020

    What's the question? 

    There are no formula for ICC profiles?

     

    When you convert from RGB to CMYK or back again, there's a Profile Connection Space, usually Lab in 'the middle'. So by the time CMYK comes into play, anything about RGB is gone. Or to put it another way, if you convert CMYK to anything, it's at one point in the conversion (PCS), Lab and anything about black generation is long gone. It's why we have and use Device Link Profiles to convert CMYK to CMYK and black gen can be honored in that process. No PCS. 

    Indeed, if you convert RGB to CMYK and back again, colors that may be clipped the first time are indeed gone and nothing can bring that back. 

    Author “Color Management for Photographers" &amp; "Photoshop CC Color Management/pluralsight"
      ceyhun_akgun
      ceyhun_akgun
      Legend
      August 27, 2020

      There is a logic error here. When CMYK returns RGB again, the COLOR RANGE returns collapsed. Lost vivid colors don't come back. For this reason, it will not work correctly even if there is a Profile.

      Graphic Designer Educator / PrePress Consultant
      Terms & ConditionsAccessibility statement
      Using the community Terms of use Privacy Cookie preferences Do not sell or share my personal information ad choicesAdChoices