Exposing Log Curves and RAW Video: The False Color Method

Shooting in logarithmic gamma profiles (such as Sony S-Log3, Canon C-Log2, or ARRI LogC) is standard operating procedure for commercial productions aiming to capture the maximum dynamic range of the sensor. However, evaluating a flat, desaturated Log image on a field monitor leads many operators into chronic underexposure.

The Mathematics of the Log Curve

Standard broadcast video (Rec.709) applies a steep contrast curve designed to match consumer displays directly. In contrast, Log curves compress high dynamic range into a mathematical function that dedicates more code values to highlight transitions and shadow roll-off.

Because the visual contrast is flattened, an image that appears “correct” to the naked eye on a monitor is frequently underexposed by one to two stops. When transformed back to standard contrast in post-production, the lifted shadows produce objectionable chromatic grain and blotchy skin tones.

Why False Color Outperforms Zebras and Waveforms

While waveform monitors are indispensable for evaluating overall scene balance, False Color is the most precise tool for exposure consistency across complex shooting schedules.

False Color assigns discrete, standardized chromatic colors to specific IRE brightness ranges:

• Purple (0 to 4 IRE): Crushed, clipped blacks.
• Blue (20 to 30 IRE): Deep shadow detail.
• Green (38 to 42 IRE): 18% Middle Grey standard target for most modern Log curves.
• Pink / Light Grey (50 to 60 IRE): Typical skin-tone range (adjust for the subject and the camera’s Log curve).
• Yellow / Orange (70 to 80 IRE): Bright highlight details.
• Red (98 to 100 IRE): Sensor clipping and total data loss.

By loading your monitor’s dedicated False Color scale corresponding to your camera’s Log profile, you eliminate subjective eye fatigue. Position an 18% grey card into the scene, adjust exposure until it paints solid green, and verify that facial highlights register in the designated skin zone.

RAW Video: Sensor Gain vs Metadata Exposure

When filming in 12-bit or 16-bit RAW video (such as ProRes RAW or REDCODE), the sensor records uncompressed sensor data without baked-in gamma curves. In RAW workflows:

• ISO is frequently a metadata tag rather than an analog gain multiplier.
• Setting your camera’s dual native ISO base correctly dictates the dynamic range split above and below middle grey.
• Nailing your sensor exposure at the hardware level ensures maximum latitude when grading extreme contrast ratios in DaVinci Resolve.