5 Replies Latest reply on May 5, 2013 6:41 AM by AttilaHan

    How images come to on the surface of our monitors ...

    AttilaHan Level 1

      I'm a newbie in color management and I want to ask a question to a real color guru ... thanks a lot in advance.

       

      When we look at the sRGB monitor, the image we see in ACR, comes to us with the following steps:

       

      1. Linear raw image,

      2. Linear RGB data after demosaicing,

      3. Linear input profile interprets the RGB data created by demosaicing process and send them to the PCS for step 4,

      4. Gamma encoded any color space we choose as a working space (ProPhoto RGB for example),

      5. sRGB, at the monitor ... we see these sRGB image on our monitors.

       

      Are all these steps correct?

      Or, any missing step?

       

      And, additionally, input profiles are always linear?

        • 1. Re: How images come to on the surface of our monitors ...
          thedigitaldog MVP & Adobe Community Professional

          First, depends on what software and where you view this data. Yes, the raw data is linearly encoded. At least in Adobe raw processors, that isn't anything you 'see and react to'. At some point, whatever happens under the hood, you've got a very wide gamut, high bit data source that when asked to soft proof to sRGB does a transform to produce that preview and resulting histogram and RGB values. What you see, what numbers you view based on a soft proof only show you what would result if you render the raw data in that fashion. ACR as yet has no soft proofing expect for the four color spaces (sRGB being one) but Lightroom does allow any RGB profiles to be used in this area. In ACR, in the workflow settings you can select sRGB, the RGB numbers and histogram are provided. There are no ICC profiles, there can be DNG profiles and I do believe but not 100% certain that those profiles react if you will, with linear data at this time in the processing path.

          • 2. Re: How images come to on the surface of our monitors ...
            D Fosse Adobe Community Professional & MVP

            Leaving the demosaicing aside, all of these are normal profile conversions. So: Inside ACR/Lightroom, it's linear ProPhoto. Then it's exported/opened into PS, with a profile conversion into sRGB/Adobe RGB/ProPhoto.

             

            But here's the thing (since you ask how it lands on the surface of the monitor):

             

            When you have ACR/Lightroom open, what you see is converted directly to the monitor profile: Linear ProPhoto > monitor profile. So it's only one step. When you look at it in Photoshop, it's sRGB/Adobe RGB/ProPhoto > monitor profile.

             

            EDIT: cross-post. I'm just trying to simplify this...

            • 3. Re: How images come to on the surface of our monitors ...
              AttilaHan Level 1

              Thank a lot Andrew, twenty-one ...

               

              I'm especially intrested in the functions of input profiles in the process.

               

              Let's leave soft proofing aside  .... and let's say camera is in JPEG mode ...

              How many steps are there in cameras for creating a JPEG image from the color management perspective?

              And, also let's leave aside the preview display on the camera LCD.

               

              Sensor gathers linear raw data and demosaicing process creates three channel, linear RGB data ... this linear RGB image is untagged and has very large gamut ... this untagged RGB data are then converted into the specified RGB space (sRGB or Adobe RGB for most of the cameras) by the input profile.

               

              So, the process in cameras for JPEG creation has the following steps: sensor raw data > untagged, very large gamut RGB by demosaicing > input profile converts the untagged, very large gamut RGB to the specified color space (sRGB or AdobeRGB) ... and then we have JPEG file in our hands.

               

              Are these steps correct?

               

              Thanks a lot for your time ...

              • 4. Re: How images come to on the surface of our monitors ...
                thedigitaldog MVP & Adobe Community Professional

                AttilaHan wrote:

                How many steps are there in cameras for creating a JPEG image from the color management perspective?

                Only the camera manufacturer knows and I doubt they are saying.

                • 5. Re: How images come to on the surface of our monitors ...
                  AttilaHan Level 1

                  Thank you Andrew for your interest ...