Import .cube LUTs as RGB curves in Blender's Video Sequence Editor (VSE) with optional grayscale conversion

March 11, 2025 · View on GitHub

https://github.com/user-attachments/assets/fd3ac91d-c23f-45cf-ac0f-8d0f04d6bccd

Installation

  1. Download the add-on: https://github.com/tin2tin/3D_Lut_Import_VSE/archive/refs/heads/main.zip
  2. Open Blender → Edit > Preferences > Add-ons.
  3. Install and enable it.
  4. Save Preferences.

Key Features

  1. LUT Import & Application Batch Process: Applies LUT to all selected non-audio strips in the VSE. Automatic Overwrite: Replaces existing "LUT RGB Curves" modifiers on strips. 3D LUT Compatibility: Handles cubic .cube LUT files, extracting their diagonal path values for RGB curves.
  2. Grayscale Conversion Desaturation Option: Toggles a Hue Correction modifier to zero saturation while preserving the original LUT’s contrast curves. (Only saturation of the Hue Correction modifier’s 2nd curve is set to Y=0; hue and value remain untouched.)
  3. Seamless Integration Shortcut Access: Available via the Shift + A Add Menu under Effects > LUT (Cube File). Diagnostic Reporting: Alerts users about invalid LUT formats or other issues.
  4. Technical Enhancements NP Interpolation: Reduces large LUT datasets to 256 points for stability. Error-Resistant Parsers: Validates LUT size headers and structure.

Usage Guide

Step 1. Prepare Your Scene

Select Strips: Choose non-audio VSE strips (video/image/visual strips).

Step 2. Import the LUT

Open the Add Menu: In the VSE, press Shift + A → Navigate to Effects → Click "LUT (Cube File)".

Navigate to your .cube LUT file (e.g., Rec709_to_P3.cube).

Optional: Check Desaturate to convert to grayscale while keeping tonal curves.

The script processes your LUT: Reduction interpolation (if needed). Modifier application over selected strips. Hue modifier with saturation zeroed added if selected (Desaturate is checked).

Step 3. Modify or Remove LUTs

Overwrite Existing LUTs: Re-run the operator on the same strips – it automatically removes old modifiers.

View Modifiers: In the VSE Properties Shelf (N), select a strip to see modifiers like "LUT RGB Curves" and "Hue" (if Desaturation is seleceted).

Requirements

Blender Version: ≥ 3.0 (tested up through 4.x). LUT Format: Standard .cube files with proper headers, e.g.: LUT_3D_SIZE 33

Example Workflow

Standard LUT Application: Select a clip → Shift-A → Effects → LUT (Cube File) → Choose LUT → Uncheck Desaturate. Result: Colors adjusted to the LUT’s RGB curves.

Grayscale Conversion:

Same as above → Check Desaturate. Result: Desaturated with contrast/preset from LUT, but no color information.