Mastering DaVinci Resolve's ColorSlice: A Comprehensive Guide to Saturation, Density, and Hue Control (and When to Avoid It for Look Development)

Cullen Kelly

Understanding the ColorSlice Tool's Setup and Purpose [00:29]

The ColorSlice tool in DaVinci Resolve is designed to precisely manipulate three core image attributes: density, saturation, and hue.

• Core Attributes: The tool primarily adjusts these three qualities.
• Control Levels: Adjustments can be made either on a global level using dedicated knobs for overall density, saturation, and hue, or for specific hues.
  • Individual Hues: Seven specific hues are predefined: Red, Skin, Yellow, Green, Cyan, Blue, and Magenta. Each of these hues has its own set of controls for density, saturation, and hue.
• Ease of Learning: Despite appearing complex with many knobs and sliders, the underlying logic is consistent across all hue adjustments, making it less overwhelming once the basic principles are understood for one hue.

Superior Global Saturation Adjustments [02:00]

One of the most valuable applications of ColorSlice is for global saturation adjustments, which the speaker praises as superior to other saturation operators in Resolve.

• Comparison with Primary Saturation: When compared to the traditional primary saturation knob in Resolve, ColorSlice's saturation produces a distinctly different and more desirable result.
  • Visual Differences: The primary saturation often makes highly colorful areas (like lips or accent lights) appear "video style" or inorganic, increasing both color and luminance.
  • ColorSlice's Organic Quality: ColorSlice, however, maintains a more "filmic" or "organic" feel, even at high strengths, because its model respects physical light.
    • Subtractive Saturation: This "subtractive saturation" model means that as saturation increases, luminance tends to decrease.
      • Physical Light Principle: A purer, more saturated color reflects less light more selectively, inherently appearing darker than a less saturated version of the same color. This physical principle is often overlooked in traditional color correction tools.

• Go-To Tool: The ColorSlice saturation knob is the speaker's preferred method for adjusting saturation on a shot-by-shot basis.

Finessing Saturation with ColorSlice [05:12]

ColorSlice allows for nuanced refinement of saturation, seamlessly moving from global adjustments to highly localized ones.

• Saturation Depth for Luminance Targeting: The "Saturation Depth" control enables users to center saturation operations around specific luminance areas.
  • Adjusting Depth:
    • Pulling Down Depth: Centers the effect more on the low-end of the image (shadows), having less effect on highlights.
    • Pushing Up Depth: Centers the effect more on the high-end of the image (highlights), having less effect on shadows.
  • Practical Application: This is useful for subtly controlling how saturation affects different parts of the image, e.g., reducing the impact on bright accent lights while preserving saturation in a subject's face.
• Hue-Based Saturation Adjustments: After global adjustments, users can further refine saturation for individual hues.
  • Example: Reducing saturation for skin tones while increasing it for cool background elements (e.g., cyan regions) to achieve a desired balance without affecting other colors.

    

The Concept of Color Density [08:13]

The video delves into the definition and application of "color density" within ColorSlice.

• Definition: Color density involves changing luminance or exposure based on saturation levels. It represents an inverse relationship where increasing saturation leads to a decrease in luminance.
• Benefits: This technique is excellent for creating depth and managing color contrast within an image.
• Pre-ColorSlice Limitations: Before ColorSlice, implementing color density effectively within Resolve was challenging.
• Visualizing Density:
  • Impact on Colorful Areas: Applying global density makes colorful areas of the image appear darker.
  • Impact on Less Colorful Areas: Areas with low saturation, like neutral walls, show minimal change with density adjustments, demonstrating that the effect is tied to color presence.
• Density as Saturation vs. Exposure/Luminance: The speaker prefers to think of density as controlling the relationship between saturation and exposure/luminance.

ColorSlice Density vs. Traditional Tools [09:49]

ColorSlice offers a superior approach to density compared to previous methods in Resolve.

• Traditional Method (Pre-ColorSlice): The closest equivalent involved combining primary saturation adjustments with "Sat vs. Lum" curves.
  • Sat vs. Lum Curve: This curve allows decreasing luminance at high saturations.
• Superiority of ColorSlice: While the traditional method attempts the same idea, ColorSlice's results are more "filmic" and "organic," making it a more effective tool for this task.

  

• Seamless Workflow for Hue-Specific Density: Just like saturation, ColorSlice allows for seamless transitions from global density adjustments to hue-specific density adjustments.
  • Example: Increasing the "red density" for a red shirt makes the red appear richer and carry more weight, a level of control that was difficult to achieve cleanly and quickly before ColorSlice.

    

When to NEVER Use ColorSlice: Look Development [12:10]

The speaker strongly advises against using ColorSlice as a look development tool for an entire film or series.

• Purpose of ColorSlice: It is designed as a color grading tool for individual shots, not for creating foundational, project-wide looks.
• Risk of Artifacting: When applying ColorSlice adjustments as part of a global look, it can introduce splotches, chatter, or noise into the image, especially in certain colors like reds and yellows.
  • Long-Term Issues: Such artifacts, if baked into a look, become difficult to rectify hundreds or thousands of shots into a project, potentially requiring a complete rebuild of the look or a switch to a different tool.
  • Higher Bar for Look Dev Tools: Look development tools must be exceptionally clean and robust, a standard ColorSlice does not meet.
• Acceptable for Shot-Level Grading: For individual shots, if an adjustment causes issues, it can be easily dialed back or achieved differently, as it only affects that single shot.

  

DaVinci Resolve's Misstep with the Skin Vector [15:28]

The speaker identifies the "skin vector" within ColorSlice as a significant design flaw in Resolve.

• Problematic Design: While other hue slices (Red, Yellow, Green, Cyan, Blue, Magenta) are logically separated, the "Skin" vector is problematic.
  • Narrow Slice: The skin slice is notably smaller (about half the size) than other hue slices.
  • Colorimetric Reality: Skin tone is not a well-separated colorometrically from reds and yellows; it's a subset within them.
• Consequences of the Skin Vector's Existence: Even without directly manipulating the skin vector, its presence can compromise results in adjacent hues.
  • Edge Conflict: The tool must make room for the skin tone vector, causing red and yellow adjustments to "hit an edge" sooner than they should. This leads to chatter and noise, particularly in reds and yellows, because these surrounding hues must accommodate the poorly defined skin tone region.

    

    

Solutions for Noisy Reds or Yellows in ColorSlice [19:07]

To address problematic or noisy results when adjusting reds or yellows in ColorSlice:

• Primary Use Case: Remember to use ColorSlice as a color grading tool for individual shots, not for establishing a project-wide look.
• Avoid Skin Tone Vector Directly: The speaker personally avoids manipulating the skin tone vector itself due to its narrowness and propensity for creating unclean operations.
• Workaround for Noise: If adjustments to reds or yellows are causing noise:
  • Move Skin Tone Vector Center: Shift the "Center" slider for the skin tone vector as far out of the way as possible.
    • For Noisy Reds: Move the skin tone center all the way to the right (counter-clockwise).
    • For Noisy Yellows: Move the skin tone center all the way to the left (clockwise).

      

• Overall Summary of Controls: The ColorSlice tool offers global controls for density, saturation, and hue, along with individual controls for each of the seven hue angles. Additional features like saturation depth and density depth follow similar logic, allowing for nuanced adjustments to how strongly saturation or density affects different luminance ranges. Saturation balance controls how "subtractive" the saturation effect is. The tool, despite initial appearance, is a powerful and approachable means to manipulate images at the grading level based on hue, density, and saturation.