vtracer/README.md

VTracer

Raster to Vector Graphics Converter

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Packages

VTracer 1.0 is a vectorization framework (pluggable frontends, curve fitters, color fitting, and output optimization) shipped across four surfaces from this repository:

Package	Registry	Source	Use
vtracer-cli	crates.io	crates/vtracer-cli	Command-line tool (vtracer binary)
vtracer	crates.io	crates/vtracer	Rust library / the framework core
vtracer	PyPI	crates/vtracer-py	Python native extension (pyo3 + maturin)
@visioncortex/vtracer	npm	nodejs	Node.js WebAssembly build, no native dependency

Introduction

visioncortex VTracer is an open source software to convert raster images (like jpg & png) into vector graphics (svg). It can vectorize graphics and photographs and trace the curves to output compact vector files.

Comparing to Potrace which only accept binarized inputs (Black & White pixmap), VTracer has an image processing pipeline which can handle colored high resolution scans. tl;dr: Potrace uses a O(n^2) fitting algorithm, whereas vtracer is entirely O(n).

Comparing to Adobe Illustrator's Image Trace, VTracer's output is much more compact (less shapes) as we adopt a stacking strategy and avoid producing shapes with holes.

VTracer is originally designed for processing high resolution scans of historic blueprints up to gigapixels. At the same time, VTracer can also handle low resolution pixel art, simulating image-rendering: pixelated for retro game artworks.

Technical descriptions of the tracing algorithm and clustering algorithm.

Desktop App (coming soon)

Cmd App

Input and output can be given as positional arguments or as named flags:

vtracer input.jpg output.svg
# equivalent to:
vtracer --input input.jpg --output output.svg

Full options (flag names are kebab-case, e.g. --filter-speckle):

Usage: vtracer [OPTIONS] [INPUT] [OUTPUT]

Arguments:
  [INPUT]   Input raster image (positional; or use --input)
  [OUTPUT]  Output SVG (positional; or use --output)

Options:
  -i, --input <INPUT>                        Path to the input raster image
  -o, --output <OUTPUT>                      Path to the output SVG
      --preset <PRESET>                      Start from a preset: bw, poster, photo
      --colormode <COLORMODE>                Color image `color` (default) or binary image `bw`
      --hierarchical <HIERARCHICAL>          Clustering: `stacked` (default) or `cutout` (seam-free mosaic)
  -m, --mode <MODE>                          Curve-fitting mode: `pixel`, `polygon`, `spline`
  -f, --filter-speckle <FILTER_SPECKLE>      Discard patches smaller than X px in size (0..=128)
  -p, --color-precision <COLOR_PRECISION>    Significant bits per RGB channel (1..=8)
  -g, --gradient-step <GRADIENT_STEP>        Color difference between gradient layers (0..=255)
  -c, --corner-threshold <CORNER_THRESHOLD>  Minimum momentary angle (degrees) to be a corner (0..=180)
  -l, --segment-length <SEGMENT_LENGTH>      Subdivide until all segments are shorter than this (3.5..=10)
  -s, --splice-threshold <SPLICE_THRESHOLD>  Minimum angle displacement (degrees) to splice a spline (0..=180)
      --path-precision <PATH_PRECISION>      Decimal places to use in path coordinates
      --palette <PALETTE>                    Fixed palette: comma-separated hex colors, e.g. '#112233,#445566'
      --palette-file <PALETTE_FILE>          Fixed palette from a file (hex colors, comma/newline separated)
      --max-colors <MAX_COLORS>              Auto-quantize to at most N colors
      --optimize <OPTIMIZE>                  Output optimization: 0 = off, 1 = quantize+simplify, 2 = + shorthands
      --threshold <THRESHOLD>                Binary mode: fixed threshold 0..=255 (foreground below it)
      --adaptive                             Binary mode: Bradley–Roth adaptive threshold (uneven lighting)
      --adaptive-window <ADAPTIVE_WINDOW>    Adaptive window size in px (0 = auto); implies --adaptive
      --adaptive-t <ADAPTIVE_T>              Adaptive sensitivity: % below local mean (default 15)
  -h, --help                                 Print help
  -V, --version                              Print version

New in 1.0

• Positional arguments — vtracer in.png out.svg.
• --hierarchical cutout is now a true seam-free mosaic (a gapless tessellation with shared boundaries), replacing the old re-clustered cutout.
• --palette / --palette-file — snap colors to a fixed palette (nearest in OKLab); --max-colors auto-quantizes the palette.
• --optimize — output size passes (coordinate quantization, redundant- point removal, relative/shorthand path encoding). Note: coordinate precision is set separately by --path-precision, the bigger size lever.
• Binary thresholding — a tunable fixed cutoff (--threshold) or Bradley–Roth adaptive thresholding (--adaptive, with --adaptive-window / --adaptive-t) for scans with uneven lighting.

Downloads

You can download pre-built binaries from Releases.

You can also install the program from source from crates.io/vtracer:

cargo install vtracer-cli

You are strongly advised to not download from any other third-party sources

Usage

# simplest form
./vtracer input.jpg output.svg

# black & white line art
./vtracer input.jpg output.svg --preset bw

# scanned/photographed line art with uneven lighting
./vtracer scan.jpg output.svg --colormode bw --adaptive

# seam-free mosaic (gapless tessellation)
./vtracer input.jpg output.svg --hierarchical cutout

# constrain to a fixed palette
./vtracer input.jpg output.svg --palette '#1b1b1b,#e0c088,#5a7d3c,#8fb0d0'

Rust Library

You can install vtracer as a Rust library.

cargo add vtracer

Python Library

vtracer is also packaged as a Python native extension (built with pyo3 + maturin, from the crates/vtracer-py crate).

pip install vtracer

import vtracer

# one-liners
vtracer.convert_file("in.png", "out.svg")
svg = vtracer.convert_bytes(open("in.png", "rb").read())

# rich, reusable config + presets
cfg = vtracer.Config(mode="polygon", hierarchical="cutout")
cfg.palette = ["#1b1b1b", "#e0c088", "#5a7d3c"]
svg = cfg.convert_bytes(data)
vtracer.Config.poster().convert_file("photo.jpg", "poster.svg")

# binary with adaptive (Bradley–Roth) thresholding
bw = vtracer.Config(color_mode="bw", adaptive=True)
svg = bw.convert_file("scan.jpg", "scan.svg")

See crates/vtracer-py for the full API.

Node.js Library

@visioncortex/vtracer is available for Node as a WebAssembly build (from the nodejs package) — image decoding and vectorization both run in wasm, so there is no native dependency. Decodes PNG, JPEG, GIF, BMP, and WebP; for other formats, decode yourself and pass raw RGBA to convertPixels.

npm install @visioncortex/vtracer

const vtracer = require('@visioncortex/vtracer');

await vtracer.convertFile('in.png', 'out.svg', { mode: 'polygon' });
const svg = vtracer.convertBuffer(buffer, { preset: 'poster' });
const svg2 = vtracer.convertPixels(rgba, width, height, { colorMode: 'bw' });

// binary with adaptive thresholding
const bw = vtracer.convertBuffer(buffer, { colorMode: 'bw', adaptive: true });

Citations

VTracer has since been cited by a few academic papers in computer graphics / vision research. Please kindly let us know if you have cited our work:

• SKILL 2023 Framework to Vectorize Digital Artworks for Physical Fabrication based on Geometric Stylization Techniques
• arXiv 2023 Image Vectorization: a Review
• arXiv 2023 StarVector: Generating Scalable Vector Graphics Code from Images
• arXiv 2024 Text-Based Reasoning About Vector Graphics
• arXiv 2024 Delving into LLMs' visual understanding ability using SVG to bridge image and text