Spline Engine

Smooth Bézier curves via vtracer. Best for photos and illustrations.

Algorithm

1. Color quantization — reduce to N colors (configurable)
2. Contour tracing — find boundaries between color regions
3. Bézier fitting — fit smooth cubic Bézier curves to contours
4. Layering — optionally stack or cutout layers

Characteristics

• Smooth curves — cubic Bézier splines
• Configurable — many parameters for fine-tuning
• Presets — bw, poster, photo for quick setup
• Larger files — more control points than PixelExact
• Input budget — images above 2 MP are downscaled before tracing (see below)

Large Images

vtracer's cost grows faster than the pixel count (on a noisy photo: 1 MP ≈ 10 s, 2 MP ≈ 38 s, 4 MP ≈ 108 s, 16 MP did not finish in 150 s). Spline output also discards fine detail anyway, so inputs above the budget are downscaled (area averaging) before tracing. The SVG keeps the original width/height and maps the traced coordinates with viewBox, so it displays at full size.

covecto big.jpg --engine spline --spline-max-mp 1 -o big.svg   # faster, smaller
covecto big.jpg --engine spline --spline-max-mp 0 -o big.svg   # trace at full size

PixelExact is never downscaled.

Example

# Default
covecto a photo
covecto photo.jpg --engine spline -o photo.svg

# Black and white
covecto photo.jpg --engine spline --preset bw -o bw.svg

# Poster effect
covecto photo.jpg --engine spline --preset poster -o poster.svg

vtracer Presets

Preset	Colors	Use Case
bw	2 (binary)	Line art, silhouettes
poster	~10	Posterization effect
photo	~30	Natural photographs

Tuning Parameters

covecto input.png --engine spline \
  --color-precision 8 \
  --corner-threshold 90 \
  --splice-threshold 45 \
  -o output.svg

See Configuration for all parameters.