Why your LUT looks flat on S-Log3 (and how to fix it in Resolve, Premiere and Final Cut)

Updated 2026-09-24 · 6 min read · by Nunik Co.

You built a LUT from a reference you love, dropped it on your S-Log3 clip, and the picture went milky: lifted blacks, grey highlights, colours that sit in the wrong place. The LUT is not broken. It was measured in one colour space and you applied it in another.

What log footage actually is

S-Log3, V-Log, C-Log3, N-Log, Apple Log and ARRI LogC are all ways of storing more dynamic range than a display can show. The camera squeezes fourteen or more stops into a flat, low contrast, low saturation image so that nothing clips in the file. Nothing about that picture is meant to be looked at. It is a container.

A Rec.709 image is the opposite: it is already display referred. The blacks are black, the whites are white, the saturation is where your eye expects it. Almost every reference still you will ever match to (a film frame, a graded screenshot, a photo you like) is Rec.709 or sRGB.

Why the LUT looks wrong

A 3D LUT is a lookup table. It says "when the input pixel is this RGB value, output that RGB value". It has no idea what the input represents. If you build the LUT from a Rec.709 original and a Rec.709 reference, every entry in the table assumes Rec.709 input.

Feed it S-Log3 and the table is answering the wrong question. Mid grey in S-Log3 sits around 41 percent; in Rec.709 it sits around 18 to 20 percent. So the LUT reads your properly exposed midtones as bright highlights and your shadows as midtones. Everything shifts up and flattens. Saturation goes the same way, because log encodes chroma in a compressed gamut the LUT never saw.

The same thing happens in reverse if you build a LUT from log frames. ChromaMimic measures colour distributions to learn the transform, and a log frame has a distribution that means nothing in display space. Match two log frames and the LUT will be flat by construction.

The fix, in one sentence

Convert log to Rec.709 first, then apply the creative LUT after that conversion. Two steps, in that order, every time.

The conversion is called a colour space transform (CST), or sometimes a technical LUT or input LUT. The camera manufacturer's official log to Rec.709 LUT is one; Resolve's built in Color Space Transform effect is a better one because it is maths rather than a fixed table.

DaVinci Resolve

1. On the Color page, add a node before your creative node.
2. Open the Effects panel, find Color Space Transform under Resolve FX Color, and drag it onto that first node.
3. Set Input Color Space and Input Gamma to match the camera. For Sony that is S-Gamut3.Cine and S-Log3. Panasonic is V-Gamut and V-Log. Canon is Cinema Gamut and Canon Log 3.
4. Set Output Color Space to Rec.709 and Output Gamma to Rec.709 (or Gamma 2.4 if you monitor that way). Leave tone mapping on its default unless the highlights clip.
5. On the next node, apply your ChromaMimic .cube. Right click the node, choose 3D LUT, and pick it.

If you are using Resolve Color Management (DaVinci YRGB Color Managed) the CST is done for you at the timeline level and you can skip the node, as long as the clip's input colour space is set correctly in the Media pool.

Premiere Pro

1. Open Lumetri Color on the clip.
2. In Basic Correction, set Input LUT to the camera manufacturer's log to Rec.709 conversion. Sony publishes these for S-Log3, Panasonic for V-Log, Canon for C-Log. Browse to the file the first time; it is remembered afterwards.
3. In Creative, set Look to your ChromaMimic .cube.

Lumetri applies Input LUT before everything else and the Creative Look after the basic corrections, which is exactly the order you want. Newer Premiere builds can also detect log footage automatically in the sequence settings; if that is on, the Input LUT step is already handled and you only add the Look.

Final Cut Pro

1. Select the clip and open the Inspector, Info tab. Switch the metadata view to Settings if you cannot see it.
2. Set Camera LUT to the matching log profile. Final Cut ships Sony, Panasonic, Canon, ARRI and others built in. This is your conversion step.
3. From the Effects browser, drag the Custom LUT effect (under Color) onto the clip, then in the Video Inspector choose your ChromaMimic .cube from its LUT menu.

The Camera LUT is applied first, at the clip level, and effects run after it. That is the correct order.

Building the match correctly in the first place

Do the conversion before you export the still you feed to ChromaMimic. Grab your original frame from a clip that already has the CST or Camera LUT applied, so the still is Rec.709. Match that to your Rec.709 reference. The .cube you get back is now a Rec.709 to Rec.709 creative LUT, which is exactly what belongs after the conversion node.

ChromaMimic has a colour space selector next to the frames. If you tell it the frames are log it warns you, and it writes a reminder into the exported .cube header so the file itself says "apply after a CST". It cannot convert log for you, because the maths depends on the camera, and pretending otherwise is how tools produce LUTs that look right on the sample and wrong on the job.

A quick sanity check on the scopes

After the CST node, before the LUT, a correctly converted log clip should show skin tones around 60 to 70 percent on the waveform and mid grey around 40 percent. If your waveform is bunched in the middle third with nothing near the top or bottom, the conversion has not happened. Fix that before you judge the LUT.