1. Copy the .3dl file into the following directory:


2. Edit the following file in your favorite text editor:


3. Look for the section in the file that specifies the display luts. It looks like this:

    - !<View> {name: None, colorspace: raw}
    - !<View> {name: sRGB, colorspace: sRGB}
    - !<View> {name: rec709, colorspace: rec709}

4. Add another view definition for your custom LUT:

    - !<View> {name: LogCRec709, colorspace: LogCRec709}

5. Go to the very end of the file, and add a colorspace definition:

  - !<ColorSpace>
    name: LogCRec709
    family: ""
    equalitygroup: ""
    bitdepth: 32f
    description: |
      Conversion from Alexa LogC to Rec. 709
    isdata: false
    allocation: uniform
    allocationvars: [-0.125, 1.125]
    from_reference: !<FileTransform> {src: LogC_to_Rec709.3dl, interpolation: linear}

6. Restart Hiero

And that should do it.

13 Responses to “Adding a .3DL file to Hiero’s Viewer”

  1. After trying this on windows , Hiero doesnt launch.

    Apparently if you change anything in the config.ocio file hiero fails to launch.

    • Mohamed,

      Sorry I’m just responding to this now. You must be extremely careful when changing config.ocio. A single curly brace that’s out of place and Hiero will not launch. I’m sure you have already figured this out, but make sure and save a backup file first, and then edit it until you get it right. Good luck.

  2. Hi, thank you for the info, but where do you ge the LogC_toRec709.3dl, because I can’t generate one in the alexa arri lut generator.


    • 4 nedwilson

      Hey there Joseph, I just made one in Nuke using the GenerateLUT node. To do this, drop a CMSTestPattern node into Nuke, set the cube size to 17. Connect a Colorspace node to the test pattern, and set the “in” to AlexaV3LogC, and the “out” to Rec.709. Last, connect a GenerateLUT node. Set the file type to .3dl, and leave everything else default. Fill in a file path for where you want to save your file, and hit “Generate and write LUT file”.

      • Thanks Ned!, you know I have a problem when I do that, I receive this error in Hiero: LogCrec709 inverse; 1 OpenColor IO Error: 3D Lusts can only e applied in the foward direction.inverse specified, and the image appears quite dark with the viewer patter in hiero.

        Don’t know what I’m doing wrong, I specially put attention to the from_reference.

        Maybe because nuke creates a 3D lut insted of a 1D lut

        • The issue was that the text that is contained within the config.ocio file has tags that are enclosed in < and >. WordPress mistakenly interprets these as HTML tags and removes them from the post. I have reformatted what I have asked to cut and paste in the original post, being sure to include all extra markup. I tested this with Hiero 1.8v2 just now, and it works just fine.

          • I found that problem before, I reviewed the other colorspaces, and I have checked multiple times the code, I tried some Luts from the generator and only the 1D didn’t give error, but the color is wrong.

          • I can see that the error is related to the Lut file,but I can’t find a solution. I’m using an Alexa Proress 4444.

  3. I’m not sure I understand the problem that you are having. Are you getting an error message where Hiero is not displaying an image and might have an error dialog, or does the image display correctly but look incorrect?

    • When Hiero starts, the error appears in the command line window that initiate with hiero in windows.
      I’m importing the Alexa proress 4444 with AlexaV3LogC color space and using the Hiero viewer with the LogCRec709 mode.

      The image is quite constrasted, deep blacks and overexposed areas.
      The colors are right and the same in Nuke (importing a alexa lut from the generator) and Davinci, but I can’t get the same color in Hiero.

      • Please cut and paste the error that you are getting in the Hiero command line window. Also, when you import these PR444 Quicktimes into Hiero, be sure and right click on them, and Set Media Colour Transform to “raw”. If you had set them to AlexaV3LogC in Hiero, using the LogCRec709 LUT will apply a double LUT, hence the colors that you are getting. It expects input data to be RAW.

        • The error is this:

          OpenColorEffectManager::createLutAndShader name: LogCRec709 inverse: 1 OpenColor
          IO Error: 3D Luts can only be applied in the forward direction. (inverse) specified.

          With raw, the results are better but not the correct ones, some overexposed areas are still there. The result don’t match resolve, nuke or after effects.

          When creating the lut in Nuke I use this in the color space:
          in : AlexaV3LogC D65 sRGB
          out :Rec709(1.95) D65 sRGB

          and as you said, only put a path and save .3dl in the generate Lut node, the other parameters are: 10bits, unput bit depth, clamp output on and autodesk flame/smoke profile.

          • Regarding the OCIO error, I had never noticed that before. We typically launch Hiero from the Finder. However, I was able to reproduce it (although the color still rendered correctly). What I had done in my example was to set up a custom colorspace in the OCIO config. After doing a little digging in the OCIO documentation, they say that the proper way to do this is to define a look, not make a colorspace. Only problem with this method is that Hiero apparently doesn’t support looks. They work fine in Nuke. So, I just sent off a bug report to The Foundry. We shall see what they say. In the meantime, thank you for letting me know about this.

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