mirror of
https://github.com/visioncortex/vtracer.git
synced 2026-09-12 07:06:03 -07:00
Chris Tsang
46a1b90ccd
An alternative region-forming frontend selected by --clustering watershed (the color_mode field is replaced by clustering: color-cluster | bw | watershed across CLI, Rust, Python, and Node — it selects the algorithm, not a color space). The algorithm is the watershed hierarchy by volume on the 4-adjacency pixel graph, implemented from the papers: Cousty, Bertrand, Najman, Couprie, "Watershed Cuts: Minimum Spanning Forests and the Drop of Water Principle", IEEE TPAMI 31(8), 2009. Najman, Cousty, Perret, "Playing with Kruskal", ISMM 2013. Edge weights are the max per-channel color difference between adjacent pixels (no gradient image); a counting-sorted Kruskal pass builds the binary partition tree as a flat parents array; a leaves-to-root pass computes subtree area and volume; each merge's persistence (the volume of the smaller side, plateau-corrected) becomes its MST edge's saliency; and cutting the hierarchy is single-linkage over MST edges below the cut level. Watershed cuts label every pixel — no watershed-line pixel class — so the output is a strict, gapless partition that drops straight into both stacked and cutout modes. Integer arithmetic and flat u32 arrays throughout; deterministic across platforms; ~66 ms on a 1400x775 photo. The one dial, --watershed-detail (0..=255), maps exponentially to a target region count (each +25.5 doubles it) since the persistence distribution is far too skewed for a linear threshold. filter_speckle absorbs undersized basins into their most color-similar neighbour rather than dropping them, preserving the partition. The largest region is emitted first as a solid full-canvas background layer so stacked mode keeps its seam-free overdraw; the mosaic flatten is unaffected. Tests: partition invariant (disjoint masks tiling the canvas), detail monotonicity, min-area absorption, determinism, watershed cases in the pipeline/golden suites, stacked-vs-cutout interior equivalence, a watershed seam test, and SegmentKey coverage for the new params.
73 lines
2.6 KiB
Markdown
73 lines
2.6 KiB
Markdown
# vtracer (Python)
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Python bindings for the [`vtracer`](https://github.com/visioncortex/vtracer)
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raster-to-vector framework. Built with [pyo3](https://pyo3.rs) +
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[maturin](https://www.maturin.rs); the core Rust crate stays pure (no I/O), and
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this crate adds image decoding and a Pythonic API.
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## Install
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```sh
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pip install vtracer
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```
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## Usage
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```python
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import vtracer
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# one-liners
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vtracer.convert_file("in.png", "out.svg")
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svg = vtracer.convert_bytes(open("in.png", "rb").read()) # -> str
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svg = vtracer.convert_pixels(rgba_bytes, width, height) # raw RGBA8
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# a rich, reusable configuration object
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cfg = vtracer.Config(mode="polygon", filter_speckle=8)
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cfg.hierarchical = "cutout" # seam-free mosaic
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cfg.palette = ["#1b1b1b", "#e0c088", "#5a7d3c"] # snap to a fixed palette
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cfg.max_colors = 8 # or auto-quantize
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cfg.optimize = 2
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svg = cfg.convert_bytes(data)
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# presets
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vtracer.Config.poster().convert_file("photo.jpg", "poster.svg")
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vtracer.Config.bw().convert_file("scan.png", "lineart.svg")
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```
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### `Config`
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Constructor keyword arguments (all optional) — also exposed as mutable
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properties, plus the presets `Config.bw()`, `Config.poster()`, `Config.photo()`:
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| arg | default | notes |
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|---|---|---|
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| `clustering` | `"color-cluster"` | `"color-cluster"`, `"bw"`, or `"watershed"` |
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| `hierarchical` | `"stacked"` | `"stacked"` or `"cutout"` (mosaic) |
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| `mode` | `"spline"` | `"pixel"`, `"polygon"`, `"spline"` |
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| `filter_speckle` | `4` | discard patches smaller than X px |
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| `color_precision` | `6` | significant bits per channel |
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| `layer_difference` | `16` | color diff between gradient layers |
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| `corner_threshold` | `60` | degrees |
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| `length_threshold` | `4.0` | px |
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| `max_iterations` | `10` | |
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| `splice_threshold` | `45` | degrees |
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| `path_precision` | `2` | output decimal places |
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| `palette` | `None` | list of `#rrggbb` strings |
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| `max_colors` | `None` | auto-quantize target |
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| `optimize` | `1` | `0` off, `1` quantize+simplify, `2` + shorthands |
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| `binary_threshold` | `128` | bw: fixed cutoff, foreground below it |
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| `adaptive` | `False` | bw: Bradley–Roth adaptive thresholding |
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| `adaptive_window` | `0` | bw adaptive: window px (`0` = auto) |
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| `adaptive_t` | `15.0` | bw adaptive: % below local mean |
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| `watershed_detail` | `128` | watershed: hierarchy cut level 0..=255 |
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Each `Config` has `convert_file(input, output)`, `convert_bytes(data, format=None) -> str`,
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and `convert_pixels(rgba, width, height) -> str`.
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## Build from source
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```sh
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maturin develop # into the active virtualenv
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maturin build --release # produce a wheel
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```
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