3 Replies Latest reply on Sep 7, 2009 10:31 AM by Bill_Janes

    Pure RAW/CR Defaults

    ViseMoD

      I'm just curious about how to force CR to show pure RAW without any changes. I mean if I set all sliders to zero, will it give me an image identical to one after Bayer demosaicing process?

        • 1. Re: Pure RAW/CR Defaults
          Thomas Knoll Level 2

          Camera Raw does not provide a way to see the pure demosaiced image, since you cannot bypass the camera profile or white balance processing.

           

          If you really want to see it, the best way would be to save the raw image as a "linear" DNG file, and then use the "-3" option on the dng_validate command line tool (part of the Adobe DNG SDK) to dump the image to a TIFF file, which you can then open in Photoshop.

           

          The image will be a lot uglier than you expect.

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          • 2. Re: Pure RAW/CR Defaults
            Jeff Schewe Level 5

            ViseMoD wrote:

             

            I'm just curious about how to force CR to show pure RAW without any changes.

             

             

            Uh, I think you are deluding yourself...there is no such thing as a RAW without any changes (unless you have actually seen what Thomas is talking about, it's pretty ugly). Raw files need SOME sort of interpretation to be visible...the only question is whether or not you understand what you are seeing? You can set everything to zero and set the point curves to linear...but all you'll really see is an ugly image, ya know?

            • 3. Re: Pure RAW/CR Defaults
              Bill_Janes Level 2

              Jeff Schewe wrote:

               

              You can set everything to zero and set the point curves to linear...but all you'll really see is an ugly image, ya know?

               

              You can set the ACR controls to linear and convert the image, but as Mr. Knoll stated, the image will still be white balanced with the camera profile applied. It will look flat, since a contrast curve has not been applied and it will be with a gamma of the space into which it was rendered (e.g. 2.2 with sRGB). If you want an image that is scene referred with a gamma of 1.0, you can use the method outlined on the ICC web site:

               

              http://www.color.org/scene-referred.xalter

               

              The image will be white balanced with the camera profile applied, but will look quite dark if not viewed in a color managed application. If you don't want white balance, you can use a specialized program such as DCRaw or Iris. I think the camera profile is still used to convert from camera RGB to XYZ RGB or something similar. The image will look dark and green (assuming it was shot in daylight with most cameras).

               

              Here are examples for clarification:

               

              ACR Default:

               

              test_ACR_default.jpg

              ACR Linear:

              test_ACR_linear.jpg

              Scene referred:

              Test_scene_noProfile.jpg

              Iris: no white balance, gamma 1.0:

               

              Test_Iris.jpg

              The Iris version is useful to check raw histograms for clipping and for sensor analysis and other specialized uses.

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