1 Reply Latest reply on Mar 24, 2013 1:52 AM by G.Hoffmann

    Why does "Gamut Warning" option gray out when setting up soft proof for Monitor RGB?

    IdamIndia Level 1

      Monitor RGB should be the smallest color gamut I believe, and so it must have the maximum gamut issue. Instead here I notice the gamut warning is grayed out. This is counter intuitive to me.

       

      Photoshop Manual says:

      "All pixels outside the gamut of the current proof profile space are highlighted in gray."

       

      Using a scanned slide in 16bit with embedded profile proPhotoRGB, produces warnings when Soft Proof is set to CMYK, but when set to MonitorRGB, the options jsut goes away (grays out!).

       

      Gamut warning 1.png

       

      Gamut warning 2.png

       

      this is for CS6.

        • 1. Re: Why does "Gamut Warning" option gray out when setting up soft proof for Monitor RGB?
          G.Hoffmann Level 3

          Soft proofing for Monitor Profile can be done by two different methods:

           

          A) View > Proof Setup > Monitor RGB

               In this case Gamut Warning is not available.

           

          B) View > Proof Setup > Custom

              Custom > Monitor RGB (Profile) by name, as below

               Preserve RGB Numbers unchecked

               In this case Gamut Warning can be activated.

           

               Illustration, please use zoom=100%:

           

          carbonell-pRGB-800px-GamWar.png

          Explanation, correction:

           

          MP:    Monitor Profile, direction XYZ --> RGB

          MP':   Inverse Monitor Profile, direction RGB ---> XYZ

           

          XYZ:  Profile Connection Space CIE(1931) XYZ

           

          Measured Monitor Profiles are mostly not Matrix Profiles but Table

          based Profiles. In this case the Profile Connection Space is Lab.

           

          MP:    Monitor Profile, direction Lab --> RGB

          MP':   Inverse Monitor Profile, direction RGB ---> Lab

           

          Lab:  Profile Connection Space CIELab

           

          In color managed applications in Photoshop MP is applied in advance to

          sending data to the graphics card VRAM.

           

          A) Soft Proofing by Monitor RGB works without any color management.

               RGB values are sent directly to the graphics card VRAM and from

               there via LUTs  (Look-up-tables) to the monitor.

               MP is not used.

           

          B) Soft proofing by Monitor Profile generates the sequence MP'·MP

              The product MP'·MP is explicitly executed. In this case one can

              compare the input of MP' and the output of MP. In any case of

              clipping these values are different (beyond ordinary numerical inaccu-

              racy) and the respective pixel can be marked by an alarm color

              (here Magenta) as a Gamut Warning.

           

          All tests by PhS CS2. Corrections and comments are appreciated.

           

          Best regards -- Gernot Hoffmann.

           

          Message was edited by: G.Hoffmann

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