radsym

WebAssembly bindings for the radsym radial symmetry detection library.

Detect circles and visualize FRST response heatmaps directly in the browser.

Building

wasm-pack build crates/radsym-wasm --target web --release

Installation

From the built package:

npm install ./crates/radsym-wasm/pkg

Or from npm (when published):

npm install @vitavision/radsym

Usage

Initialization

import init, { RadSymProcessor } from '@vitavision/radsym';

await init();
const processor = new RadSymProcessor();

Detect circles from a canvas

const canvas = document.getElementById('myCanvas');
const ctx = canvas.getContext('2d');
const imageData = ctx.getImageData(0, 0, canvas.width, canvas.height);

processor.set_radii(new Uint32Array([8, 10, 12]));
processor.set_polarity('bright');
processor.set_radius_hint(10.0);

const result = processor.detect_circles(imageData.data, canvas.width, canvas.height);
// result is Float32Array with stride 4: [x, y, radius, score, ...]
for (let i = 0; i < result.length; i += 4) {
  console.log(`Circle at (${result[i]}, ${result[i+1]}) r=${result[i+2]} score=${result[i+3]}`);
}

Visualize FRST response heatmap

const heatmap = processor.response_heatmap(imageData.data, w, h, 'hot');
// heatmap is Uint8Array of RGBA pixels (length w * h * 4)
const img = ctx.createImageData(w, h);
img.data.set(new Uint8ClampedArray(heatmap));
ctx.putImageData(img, 0, 0);

Raw FRST response

const response = processor.frst_response(imageData.data, w, h);
// Float32Array of length w * h, row-major

Gradient field

const gradient = processor.gradient_field(imageData.data, w, h);
// Float32Array with stride 2: [gx, gy, ...], length w * h * 2

Configuration

All DetectCirclesConfig fields are exposed as flat setters:

| Method | Default | Description | |--------|---------|-------------| | set_radii(Uint32Array) | [5..15] | Radii to test (pixels) | | set_alpha(f32) | 2.0 | Radial strictness exponent | | set_gradient_threshold(f32) | 0.0 | Min gradient magnitude for voting | | set_smoothing_factor(f32) | 0.5 | Gaussian smoothing sigma factor | | set_nms_radius(usize) | 5 | NMS suppression radius | | set_nms_threshold(f32) | 0.0 | NMS minimum response | | set_max_detections(usize) | 50 | Max detection budget | | set_num_angular_samples(usize) | 36 | Angular samples in annulus | | set_num_radial_samples(usize) | 3 | Radial samples in annulus | | set_annulus_margin(f32) | 0.3 | Annulus width fraction | | set_min_samples(usize) | 8 | Min gradient samples | | set_weight_ringness(f32) | 0.7 | Ringness weight in score | | set_weight_coverage(f32) | 0.3 | Coverage weight in score | | set_max_iterations(usize) | 10 | Max refinement iterations | | set_convergence_tol(f32) | 0.1 | Refinement convergence (px) | | set_polarity(str) | "both" | "bright", "dark", "both" | | set_radius_hint(f32) | 10.0 | Initial radius hypothesis | | set_min_score(f32) | 0.0 | Minimum score threshold | | set_gradient_operator(str) | "sobel" | "sobel" or "scharr" |

Output formats

| Method | Return type | Stride | Fields | |--------|------------|--------|--------| | detect_circles | Float32Array | 4 | x, y, radius, score | | frst_response | Float32Array | 1 | response value | | response_heatmap | Uint8Array | 4 | R, G, B, A | | gradient_field | Float32Array | 2 | gx, gy |

Cleanup

Call processor.free() when done to release WASM memory.