Professional Video Color Balancing in DaVinci Resolve 20: Mastering Gamma Linear and RGB Channels

Justin Vo

Introduction to Color Balancing [0:00]

• Color balancing and matching video shots during post-production is a complex task.
  • It's not based on simple formulas and heavily relies on the colorist's experience.
  • Various tools like grey cards, color checkers [0:23][Image 6], and raw data are used on set to assist.
  • Many projects might lack adequate on-set color support, leading to footage with inconsistent white balance.
• Traditional adjustments using color wheels (Lift, Gamma, Gain) or temperature/tint sliders may not be sufficient for advanced color spaces.
  • These methods often reflect color non-linearly in gamma spaces like Log, Raw, or Rec.709.
  • This non-linear reflection means adjustments don't accurately mimic the physical effects of light on the sensor.
• This video will focus on two effective techniques in DaVinci Resolve 20 [0:08][Image 5] to overcome these challenges.
  • Converting to Gamma Linear for more precise white balance.
  • Utilizing Print Light and observing individual RGB channels for accurate color matching.

White Balancing with Gamma Linear [0:39][Image 11]

• Understanding the Problem with Non-Linear Gamma Spaces [1:23]
  • When working with Log, Raw, or Rec.709 gamma spaces, color adjustments can be non-linear.
  • This means that adjusting temperature and tint doesn't accurately reflect how physical light would change.
  • This can lead to difficulties in achieving truly neutral white points across different shots.
• Converting to Gamma Linear [1:34][Image 13]
  • The key is to convert the specific node used for white balance to "Gamma Linear" mode. [2:40]
  • This transformation allows the color grading software to simulate physical light behavior more accurately. [2:57]
  • The benefit is achieving a more natural and precise "Neutral White" balance. [3:00]
• Disabling Luma Mix [3:06]
  • It's recommended to turn off the "Luma Mix" setting.
  • This prevents the software from automatically calculating and balancing luminosity when color and light adjustments are made.
• Using the Gain Wheel and Vectorscope for Adjustment [3:14]
  • Utilize the "Gain" color wheel for primary white balance adjustments.
  • Combine this with observing the Vectorscope.
  • Activate the "Show Skintone Indicator" on the Vectorscope to guide neutral skin tone adjustments. [3:20]
  • Adjust the gain wheel until the colors on the Vectorscope align towards the center, indicating neutrality, especially for skin tones. [3:42]
  • Demonstrates matching white balance across four distinct shots, showing before and after comparisons. [3:49]
• Remaining Discrepancies [4:24]
  • Even after white balance, slight color shifts may remain due to factors like different lens focal lengths or environmental light variations between shots.
  • These subtle differences are often imperceptible to the naked eye when viewing the full RGB image.

Color Matching with Print Light and RGB Channels [5:25]

• Limitations of Human Vision [5:28]
  • Human eyes are highly sensitive to light intensity but less so to subtle color variations.
  • Distinguishing minute differences between similar colors, especially in complex scenes, can be very challenging.
  • This difficulty is amplified when viewing the composite RGB image.
• Observing Individual RGB Channels [6:00][5:58][Image 17]
  • To overcome visual limitations, it's highly effective to analyze and adjust individual Red, Green, and Blue channels separately.
  • This allows for a clearer view of color distribution and discrepancies within each primary color.
• Introducing the Print Light Tool [6:18][Image 26]
  • Print Light is a powerful tool in DaVinci Resolve that simulates the light printing process used in traditional film development.
  • Unlike standard color wheels, Print Light adjusts colors by increasing or decreasing the "light" of individual RGB channels, providing a more intuitive and physically accurate way to manipulate color. [6:27][6:11][Image 22]
• Customizing Hotkeys for Efficiency [6:37]
  • To streamline the workflow, it's crucial to customize keyboard shortcuts for Print Light adjustments and RGB channel viewing.
  • Print Light Settings: Assign keys for "Full Printer Light", "Half Printer Light" (0.5 units), and "Quarter Printer Light" (0.25 units) for increasing/decreasing Red, Green, Cyan, Magenta, Yellow, Blue channels. [7:00][6:47][Image 32]
  • Channel View Settings: Assign keys to quickly switch between viewing individual Red, Green, Blue channels, and the combined RGB image. [7:50]
  • Hardware Integration: For even greater efficiency, tools like a Stream Deck Plus [6:51][Image 34] can be customized with physical buttons for these functions.
• Practical Application and Workflow [9:00][Image 39]
  • Comparing Shots: Use the "Image Wipe" feature to compare two shots side-by-side.
  • Channel-Specific Analysis:
    • Switch to the "Red" channel view [9:32][Image 40] to identify areas with excess or insufficient red information. Darker areas indicate less red, brighter areas indicate more.
    • Use Print Light to adjust the Red channel, reducing it if there's too much. [9:44][Image 43]
    • Repeat the process for the "Green" [9:40][Image 42] and "Blue" channels, adjusting Print Light values accordingly. [9:50]
  • Refining Brightness (Gamma): After color matching with Print Light, a final adjustment to the "Gamma" wheel can be made to match overall brightness if needed. [11:34]
  • Targeted Adjustments with Power Window: For extremely precise matching, use a Power Window [12:00][Image 50] to isolate specific areas, such as skin tones, and apply Print Light adjustments only to that region. [12:05][Image 55][12:07][Image 56]
  • This combined approach allows for highly accurate and consistent color matching between diverse shots.

Conclusion [12:16]

• Recap of the effectiveness of Gamma Linear conversion for white balance and Print Light/RGB channel observation for precise color matching between different shots.
• These techniques empower colorists to achieve professional and visually harmonious results in DaVinci Resolve.