3 Replies Latest reply on Jun 23, 2010 3:53 PM by Yammer

    Seeing the unseeable in ACR

    Yammer Level 4

      I work mainly in Bridge and Camera Raw, and sometimes finish images with a bit of retouching in Photoshop. Mainly, I'm either looking at Bridge's Essentials workspace and its full-screen preview, or Camera Raw.

       

      I usually work in either ProPhoto or Adobe RGB, depending on the task in hand. I've got a moderate grasp on the joys of colour management, but I'm a bit confused with the way it's displayed in Adobe Bridge and Camera Raw. I have a calibrated/profiled HP 'wide-gamut' LCD monitor.

       

      I have been working with a raw image of red tulips. Its reds and greens are pretty rich and it doesn't translate well to sRGB at all. It fairs better with Adobe RGB, but still falls short of the full image gamut. The Bridge full-screen preview looks pretty similar to the sRGB version. In fact, no matter which working colourspace you choose, the full-screen previews of the resulting JPEGs all look the same, so I'm guessing Bridge renders all previews in the sRGB colour space. Is this right?

       

      The thing I really can't get my head around is the Camera Raw preview of the tulips in ProPhoto RGB mode. It's almost as if I'm seeing the full gamut. But I can't be seeing the full thing on my HP monitor, which is supposedly similar to the AdobeRGB gamut. How is Camera Raw displaying out-of-monitor-gamut colour in the ProPhoto RGB preview?

       

      ProPhoto

      tulips-ppRGB.jpg

       

      AdobeRGB

      tulips-aRGB.jpg

       

      sRGB

      tulips-sRGB.jpg

       

      (you might need to save these to disk to see them properly colour-managed)

        • 1. Re: Seeing the unseeable in ACR
          Jeff Schewe Level 5

          Yammer P wrote:

          How is Camera Raw displaying out-of-monitor-gamut colour in the ProPhoto RGB preview?

           

          Camera Raw takes the internal color space of ProPhoto RGB colors in a linear gamma and transforms that to your monitor's ICC profile using Relative Colorimetric rendering...it's as accurate as the display in Photoshop which as you've found out is far better than Bridge. When Bridge caches raw files it uses Camera Raw to do the accurate rendering but I'm pretty sure it stores the cached results as sRGB. When displaying a high quality thumbnail or preview, it takes the sRGB thumbs or preview and transforms it to your display profile but it's considerably less accurate than Camera Raw or Photoshop.

          • 2. Re: Seeing the unseeable in ACR
            Yammer Level 4

            Many thanks, Jeff. I often have trouble getting my head around things like this, especially when I'm dealing with colours I'm not supposed to see!

             

            I suspect that the deep reds in the tulip are actually outside AdobeRGB but within my monitor's gamut. I think I assume that one colour space would always fit inside another, but they probably often overlap.

             

            I assume that the ACR histogram represents the working colour space, as it changes shape depending on the current choice. But, if the preview is an RC rendering to the monitor profile (which is bound to be a smaller gamut), I'd expect visual clipping to occur before histogram clipping.

             

            I'm just thinking out loud here because there's already too much noise inside my head I'm a hoot at parties. Feel free to correct me, if I'm lost in the woods again.

            • 3. Re: Seeing the unseeable in ACR
              Yammer Level 4

              Yammer P wrote:

               

              But, if the preview is an RC rendering to the monitor profile (which is bound to be a smaller gamut), I'd expect visual clipping to occur before histogram clipping.

              I should have said "ProPhoto RGB preview".