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The Vignette effect darkens the edges of the frame, creating a classic cinematic look that draws the viewer’s attention to the center of the image.

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Constructor

Vignette(intensity: float = 0.5, radius: float = 0.8)
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intensity
float
default:"0.5"
Darkness intensity at the edges, from 0.0 to 1.0.
  • 0.0 = no effect (original frame)
  • 1.0 = black edges (maximum vignette)
  • Values between 0 and 1 create varying degrees of darkening
Automatically clamped to [0.0, 1.0].
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radius
float
default:"0.8"
Radius of the bright center area, from 0.0 to 1.0.
  • 0.0 = very small bright area (strong vignette)
  • 1.0 = large bright area (subtle vignette)
  • Controls how far the bright area extends before darkening begins
Automatically clamped to [0.0, 1.0].

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Examples

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Basic Vignette

from movielite import VideoClip, vfx

# Default vignette
clip = VideoClip("input.mp4")
clip.add_effect(vfx.Vignette())

# Subtle vignette
clip.add_effect(vfx.Vignette(intensity=0.3, radius=0.9))

# Strong vignette
clip.add_effect(vfx.Vignette(intensity=0.8, radius=0.6))

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Cinematic Look

from movielite import VideoClip, vfx

clip = VideoClip("input.mp4")

# Classic cinema vignette
clip.add_effect(vfx.Vignette(intensity=0.6, radius=0.7))

# Combine with color grading for cinematic feel
clip.add_effect(vfx.Saturation(1.2))
clip.add_effect(vfx.Contrast(1.3))
clip.add_effect(vfx.Vignette(intensity=0.5, radius=0.75))

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Extreme Vignette

from movielite import VideoClip, vfx

# Tunnel/spotlight effect
clip = VideoClip("input.mp4")
clip.add_effect(vfx.Vignette(intensity=0.95, radius=0.4))

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How It Works

The vignette effect creates a radial gradient that darkens pixels based on their distance from the center:
  1. Calculate distance: For each pixel, compute normalized distance from center
  2. Create mask: Generate radial gradient based on distance and radius
  3. Apply intensity: Scale the mask by the intensity parameter
  4. Multiply: Apply mask to frame to darken edges

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Mathematical Formula

# Normalized distance from center
dist = sqrt(((x - cx) / w)² + ((y - cy) / h)²)

# Vignette mask
mask = clip(1.0 - (dist / radius), 0, 1)
mask = 1.0 - (1.0 - mask) × intensity

# Apply to frame
result = frame × mask
Where:
  • (cx, cy) = center of frame
  • (w, h) = frame dimensions
  • clip() = clamp function
Source: src/movielite/vfx/vignette.py:6-69

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Parameter Effects

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Intensity Comparison

IntensityVisual Effect
0.0No vignette (original)
0.2Very subtle darkening
0.5Moderate vignette (default)
0.8Strong darkening
1.0Black edges

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Radius Comparison

RadiusVisual Effect
0.3Small bright center (spotlight)
0.5Medium bright area
0.8Large bright area (default)
1.0Very subtle vignette

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Combining with Other Effects

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Vintage Film Look

from movielite import VideoClip, vfx

clip = VideoClip("input.mp4")
clip.add_effect(vfx.Sepia(intensity=0.8))
clip.add_effect(vfx.Contrast(0.9))
clip.add_effect(vfx.Vignette(intensity=0.7, radius=0.6))

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Modern Cinematic

clip = VideoClip("input.mp4")
clip.add_effect(vfx.Saturation(1.3))
clip.add_effect(vfx.Contrast(1.2))
clip.add_effect(vfx.Brightness(0.95))
clip.add_effect(vfx.Vignette(intensity=0.5, radius=0.75))

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Drama/Horror

clip = VideoClip("input.mp4")
clip.add_effect(vfx.Saturation(0.7))  # Desaturate
clip.add_effect(vfx.Brightness(0.8))  # Darken
clip.add_effect(vfx.Contrast(1.4))    # High contrast
clip.add_effect(vfx.Vignette(intensity=0.85, radius=0.5))  # Strong vignette

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Soft Focus Portrait

clip = VideoClip("input.mp4")
clip.add_effect(vfx.Blur(intensity=3.0))
clip.add_effect(vfx.Brightness(1.1))
clip.add_effect(vfx.Vignette(intensity=0.4, radius=0.85))

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Performance Considerations

The vignette effect uses mask caching for optimal performance:
  • Mask is computed once per frame size
  • Cached masks are reused for subsequent frames
  • Very fast even at high resolutions
  • Negligible performance impact

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Caching Behavior

# First frame at 1920×1080: creates mask (~1ms)
# Subsequent frames: uses cached mask (~0.01ms)

# If resolution changes: creates new mask
# Both masks are cached independently
The mask multiplication is the only per-frame operation, which is extremely fast (sub-millisecond for most resolutions).

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Advanced Usage

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Animated Vignette

While the Vignette effect doesn’t support animation directly, you can create custom animated vignettes: 
from movielite import VideoClip, vfx
import math

clip = VideoClip("input.mp4")

# Apply different vignettes to different sections
# (This requires custom implementation or multiple clips)

# Alternative: Combine with fade for gradual vignette
clip.add_effect(vfx.FadeIn(2.0))
clip.add_effect(vfx.Vignette(intensity=0.6, radius=0.7))

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Custom Vignette Shapes

The current implementation creates circular/elliptical vignettes. For custom shapes, you would need to:
  1. Extend the Vignette class
  2. Override the mask generation logic
  3. Use custom distance calculations (e.g., rectangular, diamond)

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Technical Details

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Distance Calculation

The effect normalizes distances by dividing by frame dimensions: 
dist_from_center = sqrt(((X - center_x) / w)² + ((Y - center_y) / h)²)
This ensures consistent vignette shape across different aspect ratios.

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Mask Generation

The mask is created using NumPy’s ogrid for efficient coordinate grid generation: 
Y, X = np.ogrid[:h, :w]
This is more memory-efficient than meshgrid for this use case.

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Frame Multiplication

The mask is applied using floating-point multiplication and converted back to uint8: 
result = (frame.astype(np.float32) * mask).astype(np.uint8)

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Visual Examples

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Intensity Variations (radius=0.7)

Intensity 0.0: ⚪⚪⚪⚪⚪  (no vignette)
Intensity 0.3: ⚪⚪⚪⚫⚫  (subtle)
Intensity 0.6: ⚪⚪⚫⚫⚫  (moderate)
Intensity 1.0: ⚪⚫⚫⚫⚫  (strong)

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Radius Variations (intensity=0.6)

Radius 0.3: ⚪⚫⚫⚫⚫  (small bright area)
Radius 0.5: ⚪⚪⚫⚫⚫  (medium)
Radius 0.8: ⚪⚪⚪⚫⚫  (large bright area)
Radius 1.0: ⚪⚪⚪⚪⚫  (very subtle)

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Common Use Cases

  1. Cinematic Look: intensity=0.5-0.7, radius=0.7-0.8
  2. Portrait Focus: intensity=0.4-0.6, radius=0.8-0.9
  3. Dramatic Effect: intensity=0.7-0.9, radius=0.5-0.6
  4. Subtle Enhancement: intensity=0.2-0.3, radius=0.9-1.0
  5. Spotlight Effect: intensity=0.8-1.0, radius=0.3-0.5

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See Also

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