Linear to Log for Film Emulation in Darktable - Are 1D LUTs possible?

[Xavier_Bourque]

@priort

For your current framework as presented would something like this be a candidate??

Fresh LUTs

Yes. You can use any LUT on FreshLUTs in Darktable (as long as you ‘bake’ them in Resolve). Remember that no baking / Resolve would be required if Darktable had proper ‘log’ shapers built-in the to LUT3D module (or if Darktable implemented OCIO).

@priort

the four modules in the OCiO/ACES section

These nodes are not connected to anything in the node graph. This means these nodes are not currently in use. FileLUT and OCIOFileTransform are the nodes that you use in Fusion to load and apply a .cube file (i.e. the equivalent of the DT LUT3D module).

@priort

the main string of modules across the middle makes the “baked” in LUT and the string of 4 at the end are added in the case where you want to preview the lut on a DT export that is generated with unbreak??

Yes. Exactly.

@priort

If I have a lut with a similar gamut and color space as the one you used I would guess I can simply plug that in…

Yes. Exactly. Simply adjust the settings of the FileLUT node to your desired .cube file.

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Here is a Fusion comp file already setup. To open it in Resolve, go to File → Import → Fusion Composition

Darktable_LUT_baker_v02.zip (1.4 MB)

(I’ve also included the original LUT from Freshluts and the ‘baked’ LUT ready to use in Darktable).

To bake your own LUTs:
Make sure the Inspector is enabled (top right). Click on any node in the node graph to adjust its settings. Use the ‘1’ and ‘2’ hotkeys to view the output of the selected node in the left/right viewers. The triangles on the nodes are inputs (yellow = main input, blue=mask, green=secondary). The squares are outputs.

Once the .comp file is loaded, you need to adjust a few things (numbers refer to the notes in the Fusion node graph).

03- Adjust the output colorspace/gamma of ColorSpaceTransform1 to whatever your LUT is expecting on input (i.e. sLog3 / sGamut3)

04- Adjust the LUT File path of FileLUT1 to your desired LUT (i.e. C:\some\folder\S-LOG3_to_Rec709_v6.cube)

05- Adjust the input colorspace/gamma of ColorSpaceTransform2 to whatever your LUT is supposed to output (i.e. rec709/rec709)

07- Adjust the Filename of LUTCubeAnalyzer1 to where you want to write your ‘baked’ LUT for Darktable. (i.e. C:\some\folder\myDarktable3DLUT.cube) Click ‘Write File’ to write the cube file to disk.

08- (Optional) if you desire to preview your LUT, replace MediaIn1 with an ‘unbreakLOG’ image exported from Darktable (see notes). Drag and drop your image from a File Explorer to the Media Pool, then drag from the Media Pool to the node graph.

Have fun, good luck!

–X