LUT in track filter, level filter in clip

Help/How To
1

I’m using DJI action4 to shoot d-log videos. Then I put official action4 LUT in track filter to apply to all the clips. For individual clip, different level filter setting is used to get correct exposure.
I just realized that filter sequence does matter. Swapping LUT and level filter makes difference. If the LUT is put in track filter, it will be done after the level filter in the clips.
Which way gets better dynamic range? LUT first or level first?

2

Level first. The LUT will push log footage near the limits of pure black and white. Any exposure lift after the LUT will risk clipping the highlights and raising lost data in crushed shadows, resulting in banding or high noise. Any exposure drop after the LUT would risk creating gray blobs where highlights had clipped and can’t be recovered.

Some processes will be backwards from a Resolve workflow. This is not a 16-bit floating-point working space where clipping can be recovered, unless using the GPU Effects side. This is an 8-bit integer space. So, some processes have to be done out of usual order to protect from clipping.

EDIT: Of course, it is fine to add another level filter and play with midtones after a LUT. My recommendation was to get the black and white points dialed in before the LUT so that major exposure changes that risk clipping would not happen after the LUT.

3

After some experiments, I think for action4 log file with its official LUT, the LUT should be the first.
The official LUT normalize the log file. It didn’t provide some serious effect but only normalize the log data. If we have a normalized clip, I think you are right (do the level filter before LUT).
I have to put the official LUT in every clip, because the track filter will be done after clip filter.

4

It all depends on how hard the exposure levels are being pushed, and whether you want max tonality to be in the shadows, midtones, or highlights. Experimenting will be required for best results, as you did.

5

Just my opinion but works for me:

  • Official DJI LUT (to bring flat video back to REC709)
  • Levels
  • Stylistic LUT
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6

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