speedy-vision
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GPU-accelerated Computer Vision for JavaScript
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HTML
<!--
speedy-vision.js
GPU-accelerated Computer Vision for JavaScript
Copyright 2020-2022 Alexandre Martins <alemartf(at)gmail.com>
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
image-features.html
Feature detection in an image
-->
<html>
<head>
<meta charset="utf-8">
<meta name="description" content="speedy-vision.js: GPU-accelerated Computer Vision for JavaScript">
<meta name="author" content="Alexandre Martins">
<title>Speedy feature detection in an image</title>
<script src="../dist/speedy-vision.js"></script>
<link href="style.css" rel="stylesheet">
</head>
<body>
<h1>Finding features in an image</h1>
<form autocomplete="off">
<div>
<label for="sensitivity">Sensitivity</label>
<input type="range" min="0.0" max="0.99" value="0.5" step="0.01" id="sensitivity">
</div>
<div>
<label for="multiscale">Multi-scale</label>
<input type="checkbox" id="multiscale">
</div>
</form>
<div>
<span id="status"></span>
<canvas id="canvas-demo"></canvas><br>
</div>
<img src="../assets/masp.jpg" title="Free photo by ckturistando (pexels.com)" hidden>
<script>
window.onload = async function()
{
// form components
const sensitivity = document.getElementById('sensitivity');
const multiscale = document.getElementById('multiscale');
// tell Speedy to load the image
const image = document.querySelector('img');
const media = await Speedy.load(image);
// create the pipeline
const pipeline = Speedy.Pipeline();
const source = Speedy.Image.Source();
const greyscale = Speedy.Filter.Greyscale();
const pyramid = Speedy.Image.Pyramid();
const harris = Speedy.Keypoint.Detector.Harris();
const sink = Speedy.Keypoint.Sink();
source.media = media;
harris.capacity = 8192;
source.output().connectTo(greyscale.input());
greyscale.output().connectTo(pyramid.input());
pyramid.output().connectTo(harris.input());
harris.output().connectTo(sink.input());
pipeline.init(source, greyscale, pyramid, harris, sink);
// find & render features
const canvas = createCanvas(media.width, media.height, image.title);
async function update()
{
// multiscale?
harris.levels = multiscale.checked ? 8 : 1;
// adjust sensitivity
harris.quality = 1 - sensitivity.value;
// find features
const { keypoints } = await pipeline.run();
// render features
draw(media, canvas);
renderFeatures(canvas, keypoints);
renderStatus(keypoints);
}
update();
// recalculate feature points
// when changing the controls
sensitivity.oninput = update;
multiscale.oninput = update;
}
function createCanvas(width, height, title)
{
const canvas = document.getElementById('canvas-demo') || document.createElement('canvas');
canvas.width = width;
canvas.height = height;
canvas.title = title;
if(!document.body.contains(canvas))
document.body.appendChild(canvas);
return canvas;
}
function renderFeatures(canvas, features, size = 2, color = 'yellow')
{
const context = canvas.getContext('2d');
context.beginPath();
for(let feature of features) {
let radius = size * feature.scale;
// draw scaled circle
context.moveTo(feature.x + radius, feature.y);
context.arc(feature.x, feature.y, radius, 0, Math.PI * 2.0);
// draw rotation line
const sin = Math.sin(feature.rotation);
const cos = Math.cos(feature.rotation);
context.moveTo(feature.x, feature.y);
context.lineTo(feature.x + radius * cos, feature.y + radius * sin);
}
context.strokeStyle = color;
context.stroke();
}
function renderStatus(features)
{
const status = document.getElementById('status');
status.innerText = `Keypoints: ${features.length}`;
}
function draw(media, canvas, x = 0, y = 0, width = media.width, height = media.height)
{
const ctx = canvas.getContext('2d');
ctx.drawImage(media.source, x, y, width, height);
}
</script>
<mark>Powered by <a href="https://github.com/alemart/speedy-vision">speedy-vision.js</a></mark>
</body>
</html>