Lookup Tables (LUTs) are among the most powerful tools in a modern colorist's arsenal. However, slapping a creative LUT directly on raw footage without proper exposure correction is one of the most common mistakes editors make.
1. What Exactly is a 3D LUT?
A 3D LUT maps input colors to output colors across three axes: red, green, and blue. Unlike simple 1D LUTs that only alter luminance or individual channels independently, a 3D LUT transforms complex hue, saturation, and lightness relationships simultaneously.
2. Log vs. Rec.709: The Order of Operations
Always correct before you grade. The golden rule of using creative LUTs is to normalize your footage first:
- Node 1 (Exposure & Contrast): Balance your lift, gamma, and gain so shadows rest between 0-10 IRE and highlights do not clip above 90 IRE.
- Node 2 (White Balance): Ensure neutral whites and realistic skin tones.
- Node 3 (Color Space Transform / Normalization): Convert your camera's log profile (e.g., Sony S-Log3, Canon C-Log) to Rec.709.
- Node 4 (Creative LUT): Apply your Nexaura LUT at 60-80% opacity for a tasteful, cinematic feel.
3. Protecting Skin Tones
Always inspect your Vectorscope. Skin tones should align along the dedicated skin-tone indicator line regardless of ethnicity. If a stylistic LUT pushes faces into green or magenta casts, dial down the LUT intensity or use a qualifier key to preserve the skin tones.
