Files
vtracer/README.md
T
Chris Tsang abe21658dc Make filter_speckle a finish-phase filter, tunable without re-clustering
Speckle removal moves out of the frontends into Segmentation::filter_speckle,
applied in the finish phase. The color frontend now clusters with
good_min_area = 0 and the binary frontend emits every cluster, so the cached
segmentation retains all regions and the speckle threshold can be retuned via
finish() with no re-clustering. Pipeline gains a speckle_area field
(Config sets it from filter_speckle^2).

Frontend structs drop their filter_speckle_area field. Output on clean images
is unchanged (golden/equivalence pass unblessed); noisy images are filtered
downstream instead of during clustering. Adds a test tuning filter_speckle on
one cached segmentation.

Add finish-phase thin-strand filter (restores thread-like rejection)

good_min_area = 0 disabled visioncortex's thread-like rejection (which was
gated on good_min_area > 0). Reintroduce it in our repo as a finish-phase
step: Segmentation::filter_thin drops regions whose perimeter >= area
(average thickness under ~2px), using the same Shape::image_boundary_list
metric so the heuristic matches. It's toggleable on a cached segmentation
(Config::filter_thin, on by default), unlike the clustering-time version.

Exposed via CLI --keep-thin, Python filter_thin, and Node filterThin. Adds
RegionMask::perimeter/is_thin and a reuse test toggling it on one cached
segmentation. Clean-image goldens are unaffected (large regions aren't thin).

README: document binary thresholding, --keep-thin, and finish-phase filters

Add the new CLI flags (--threshold, --adaptive, --adaptive-window,
--adaptive-t, --keep-thin) to the options block and "New in 1.0"; note that
--optimize is encoding-only (precision is --path-precision) and that speckle/
thin filtering run after clustering. Add adaptive-threshold examples for CLI,
Python, and Node.

Return speckle/thin filtering to clustering (fix gum-tree regression)

good_min_area is visioncortex's clustering `deepen` gate, not a speckle
post-filter: it decides whether a small or thread-like patch is absorbed
into its nearest-color neighbour or kept as its own layer, and it enables
the thread-like rejection (perimeter < area). An earlier change set it to 0
to make filter_speckle "retunable downstream", which disabled the thin
check and reshaped the whole hierarchy — dissolving gradient-boundary
structure that clustering is meant to absorb. The Gum Tree preset's central
trunk vanished at gradient-step ~26 where the pre-1.0 path held it to 128.
Clean-logo goldens couldn't exercise it, so it shipped green.

Follow the proven webapp model instead: speckle lives inside clustering
(good_min_area = filter_speckle^2 for the colour frontend; a post-cluster
size gate for the binary frontend). The segment/finish split stays — it is
the progressive model (cluster once, re-run colour/curve/optimize cheaply);
clustering params (speckle, colour precision, layer difference, binary
threshold) re-segment.

Remove the downstream band-aids: Segmentation::filter_speckle/filter_thin,
RegionMask::perimeter/is_thin, the pipeline speckle_area/filter_thin fields,
Config::filter_thin, CLI --keep-thin, Python filter_thin, Node filterThin.
Update the two reuse tests that encoded the wrong contract and the binary
threshold test to use BinaryFrontend::min_area. All goldens, equivalence,
progress, and reuse tests pass.
2026-07-25 16:08:10 +01:00

208 lines
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<div align="center">
<img src="docs/images/visioncortex-banner.png">
<h1>VTracer</h1>
<p>
<strong>Raster to Vector Graphics Converter</strong>
</p>
<h3>
<a href="https://www.visioncortex.org/vtracer-docs">Article</a>
<span> | </span>
<a href="https://www.visioncortex.org/vtracer/">Web App</a>
<span> | </span>
<a href="https://github.com/visioncortex/vtracer/releases">Download</a>
</h3>
<p>
<a href="https://crates.io/crates/vtracer"><img src="https://img.shields.io/crates/v/vtracer.svg?label=crates.io%20%7C%20vtracer" alt="Rust library on crates.io"></a>
<a href="https://crates.io/crates/vtracer-cli"><img src="https://img.shields.io/crates/v/vtracer-cli.svg?label=CLI%20%7C%20vtracer-cli" alt="CLI on crates.io"></a>
<a href="https://pypi.org/project/vtracer/"><img src="https://img.shields.io/pypi/v/vtracer.svg?label=PyPI%20%7C%20vtracer" alt="Python package on PyPI"></a>
<a href="https://www.npmjs.com/package/@visioncortex/vtracer"><img src="https://img.shields.io/npm/v/@visioncortex/vtracer.svg?label=npm%20%7C%20%40visioncortex%2Fvtracer" alt="Node package on npm"></a>
</p>
</div>
## 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](https://crates.io/crates/vtracer-cli) | [`crates/vtracer-cli`](crates/vtracer-cli) | Command-line tool (`vtracer` binary) |
| `vtracer` | [crates.io](https://crates.io/crates/vtracer) | [`crates/vtracer`](crates/vtracer) | Rust library / the framework core |
| `vtracer` | [PyPI](https://pypi.org/project/vtracer/) | [`crates/vtracer-py`](crates/vtracer-py) | Python native extension (pyo3 + maturin) |
| `@visioncortex/vtracer` | [npm](https://www.npmjs.com/package/@visioncortex/vtracer) | [`nodejs`](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](http://potrace.sourceforge.net/) 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](https://helpx.adobe.com/illustrator/using/image-trace.html), 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](https://www.visioncortex.org/vtracer-docs) and [clustering algorithm](https://www.visioncortex.org/impression-docs).
## Desktop App (coming soon)
![screenshot](docs/images/desktop-app.png)
## Cmd App
Input and output can be given as positional arguments or as named flags:
```sh
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`):
```sh
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: BradleyRoth 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
**BradleyRoth adaptive** thresholding (`--adaptive`, with `--adaptive-window`
/ `--adaptive-t`) for scans with uneven lighting.
## Downloads
You can download pre-built binaries from [Releases](https://github.com/visioncortex/vtracer/releases).
You can also install the program from source from [crates.io/vtracer](https://crates.io/crates/vtracer):
```sh
cargo install vtracer-cli
```
> You are strongly advised to not download from any other third-party sources
### Usage
```sh
# 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`](https://crates.io/crates/vtracer) as a Rust library.
```sh
cargo add vtracer
```
### Python Library
[`vtracer`](https://pypi.org/project/vtracer/) is also packaged as a Python native extension (built with [pyo3](https://github.com/PyO3/pyo3) + [maturin](https://www.maturin.rs), from the `crates/vtracer-py` crate).
```sh
pip install vtracer
```
```python
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 (BradleyRoth) thresholding
bw = vtracer.Config(color_mode="bw", adaptive=True)
svg = bw.convert_file("scan.jpg", "scan.svg")
```
See [`crates/vtracer-py`](crates/vtracer-py/README.md) for the full API.
### Node.js Library
[`@visioncortex/vtracer`](https://www.npmjs.com/package/@visioncortex/vtracer) is available for Node as a WebAssembly build (from the [`nodejs`](nodejs/README.md) 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`.
```sh
npm install @visioncortex/vtracer
```
```js
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](https://www.researchgate.net/publication/374448489_Framework_to_Vectorize_Digital_Artworks_for_Physical_Fabrication_based_on_Geometric_Stylization_Techniques)
+ arXiv 2023 [Image Vectorization: a Review](https://arxiv.org/abs/2306.06441)
+ arXiv 2023 [StarVector: Generating Scalable Vector Graphics Code from Images](https://arxiv.org/abs/2312.11556)
+ arXiv 2024 [Text-Based Reasoning About Vector Graphics](https://arxiv.org/abs/2404.06479)
+ arXiv 2024 [Delving into LLMs' visual understanding ability using SVG to bridge image and text](https://openreview.net/pdf?id=pwlm6Po61I)