Secondary Color Correction / Selective Grading

Definition

Secondary Color Correction (Secondary Correction) is the precise adjustment of specific color ranges, luminance ranges (brightness), or spatial regions of an image after primary color correction (Lift/Gamma/Gain) has been performed.

While primary correction affects the entire image, secondary correction enables selective, targeted adjustments:

• Color-Selective: Only red areas, only green areas, etc.
• Luminance-Selective: Only bright areas, only dark areas
• Spatially-Selective: Only a specific region of the image (with Power Windows)

Technical Methods for Secondary Isolation

Method 1: Hue-Range Isolation (Color-Based)

Definition:
Isolate pixels that have a specific hue, independent of saturation or brightness.

Practical Application:

Example: Correct all red pixels
- Range: Red (0-30 degrees on the hue wheel)
- All pixels with this hue are isolated
- Other colors remain unchanged

Use Cases:

• Lip correction (only red lips)
• Sky correction (only blue skies)
• Green screen keying (only green pixels)
• Color casting (e.g., green tint on faces)

Software in DaVinci Resolve:

Node > Qualifier
- Select: Hue Range
- Adjust: Saturation, Hue, Lightness

Method 2: Luminance-Range Isolation (Brightness-Based)

Definition:
Isolate pixels based on their brightness (independent of color).

Practical Application:

Example: Adjust highlights only
- Range: Lights (75-100% brightness)
- All bright pixels are isolated
- Shadows and midtones remain unchanged

Use Cases:

• Reduce highlight clipping (overexposed areas)
• Preserve shadow detail (dark areas)
• Contrast adjustment
• Dynamic range compression

Software in DaVinci Resolve:

Node > Qualifier
- Select: Luminance Range
- Adjust: Exposure, Gamma, Saturation

Method 3: Spatial/Keying Isolation (Spatial)

Definition:
Isolate pixels based on their spatial position using masks/windows.

Practical Application:

Example: Correct only an actor's face
- Create window/mask around face
- Correction applies only within the mask
- Outside the mask remains unchanged

Use Cases:

• Correct individual actors
• Adjust background separately
• Vignetting effect
• Subject isolation

Software in DaVinci Resolve:

Power Windows Node
- Shapes: Circular, Elliptical, Polygon, Bezier
- Feathering: Soft transitions
- Motion: Tracking for moving masks

Method 4: Saturation-Range Isolation

Definition:
Isolate pixels based on their saturation (color intensity).

Practical Application:

Example: Modify only low-saturation colors
- Range: Low saturation (0-30%)
- Desaturated-looking material is isolated
- Highly saturated colors remain unchanged

Use Cases:

• Desaturate for black & white or desaturated look
• Selective saturation boost
• Skin tone isolation (less saturated)
• Color cast removal

Practical Secondary Grading Scenarios

Scenario 1: Skin Tone Isolation and Corrections

Problem: Different actors with various skin types require subtle color corrections.

Workflow:

1. Primary Grade: Perform general image grading
2. Secondary - Hue Range:

• Select red-orange range (skin tone area)
• Reduce saturation slightly (less saturated)
• Shift hue slightly toward yellow (warmer)
• Optionally boost luminance for "glowing" skin

1. Validation:

• All skin tones should be consistent
• Other colors remain unchanged
• Natural, non-graded appearance

Result: Professional skin tone grading

Scenario 2: Sky and Background Correction

Problem: Sky is too bright/washed out, foreground looks good.

Workflow:

1. Create Power Window:

• Draw polygon or bezier shape around sky
• Set soft feathering transitions (~30 pixels)

1. Inside Window Grade:

• Reduce exposure (sky darker)
• Increase saturation (sky more vivid blue)
• Optionally shift hue toward blue (cooler)

1. Foreground remains unchanged:

• Only inner mask is adjusted
• Transition is smooth via feathering

Result: Dramatic sky, foreground unchanged

Scenario 3: Remove Red Eyes and Highlights

Problem: Reflections in eyes or glasses are incorrectly colored.

Workflow:

1. Hue-Range Isolation:

• Select: Hue of the incorrect reflection
• Reduce saturation to zero (desaturate)
• Optionally boost luminance slightly (less dark)

1. Alternative: Power Window:

• Small circular window around eye
• Adjust saturation and exposure
• Very fine feathering for natural transition

Result: Natural-looking eyes without incorrect reflections

Scenario 4: Color Grading for Emotional Effect

Problem: Scene with two actors - one is "warm" and friendly, one is "cool" and suspicious.

Workflow:

1. Actor A (warm):

• Power Window around Actor A
• Shift gamma toward orange/yellow
• Increase saturation slightly
• Result: Warm, inviting

1. Actor B (cool):

• Power Window around Actor B
• Shift gamma toward cyan/blue
• Keep saturation consistent or reduce
• Result: Cool, calculating

1. Background:

• Remain neutral or subtly support
• Not overly dominant

Result: Visual character definition through color

Secondary Correction Tools in DaVinci Resolve

Qualifier Node

Function:
Isolates pixels based on color value (Hue, Saturation, Luminance)

Interface:

Qualifier
├── Select
│ ├── Hue Range (color selection)
│ ├── Saturation Range
│ └── Luminance Range
├── Range Selection
│ ├── Inside / Outside toggleable
│ └── Softness for feathering
└── Adjustments (like primary correction)

Practical Tips:

• Eyedropper: Click on color for automatic selection
• Range Expansion: Fine-tune range with sliders
• Feathering: "Softness" slider for smooth transitions
• Invert: Select everything EXCEPT the range

Power Windows Node

Function:
Isolates spatial areas with masks/shapes

Available Shapes:

• Rectangle: Rectangular, for structured areas
• Circular/Ellipse: Round, for objects
• Polygon: Multiple points, for complex shapes
• Bezier: Smooth curves, for organic shapes
• Paint: Freehand drawing

Motion Tracking:

• Automatic tracking for moving objects
• Keyframe-based for precise control
• Adjustable strength and feathering

Node Chaining for Secondary Grading

Efficient Workflow:

Node 1: Primary Color Correction (Lift/Gamma/Gain)
├── Base grade for entire image
│
Node 2: Hue Range Qualifier #1 (e.g., Skin)
├── Skin tone isolation and adjustment
│
Node 3: Hue Range Qualifier #2 (e.g., Sky)
├── Sky isolation and adjustment
│
Node 4: Power Window (e.g., Face)
├── Individual actor corrections
│
Node 5: Finalizer/Viewing
└── For monitoring and export

Advantages of This Structure:

• Each adjustment is modular
• Easy changes (all nodes can be adjusted)
• Non-destructive editing (original unchanged)

HSL vs. RGB Secondary Correction

HSL (Hue, Saturation, Lightness)

Advantages:

• Intuitive for color changes
• Hues directly manipulable
• Perceptually uniform

Disadvantages:

• Mathematically complex
• RGB channels internally complicated
• Less precise for subtle adjustments

RGB (Red, Green, Blue Channels)

Advantages:

• Mathematically simple
• Full control over channels
• Scientifically precise

Disadvantages:

• Not intuitive for color concepts
• Difficult to visualize
• Requires mathematical understanding

Industry Standard: HSL for grading (intuitive), RGB for compositing (precise)

Secondary Correction Mistakes and Solutions

Best Practices for Secondary Grading

Rule 1: Primary First, Then Secondary

• Never perform secondary corrections before primary
• Primary grading foundation must be solid
• Secondary adjustments build upon primary

Rule 2: Work Subtly

• Secondary adjustments should be barely noticeable
• If it looks obviously "graded," it's too aggressive
• 3-5% saturation change is often sufficient
• Hue shifts: Maximum 5-10 degrees

Rule 3: Feathering is Key

• Hard mask transitions look unrealistic
• Generous feathering (30-100 pixels depending on size)
• Soft transitions are a sign of professional work

Rule 4: Don't Use Too Many Qualifiers

• Maximum 3-5 hue-range qualifiers per timeline
• Too many = rendering performance issues
• Too many = complex to manage

Rule 5: Validate Motion Tracking

• Don't blindly trust tracking
• Check samples at different frames
• For errors: Manually keyframe problem areas

Comparison: Secondary Correction vs. Color Wheels

Summary

Secondary color correction is the advanced tool for precise, targeted adjustments in film production. The ability to isolate and correct specific color ranges, brightness ranges, or spatial regions distinguishes professional grading from standard grading. Mastering hue-range qualifiers, luminance ranges, and power windows is essential for high-end color grading.