speedy-vision
Version:
GPU-accelerated Computer Vision for JavaScript
367 lines (315 loc) • 11 kB
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.
warping.html
Image warping demo
-->
<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>Image warping</title>
<script src="../dist/speedy-vision.js"></script>
<link href="style.css" rel="stylesheet">
</head>
<body>
<h1>Image warping</h1>
<form>
<div>
Select the
<select id="template"></select>
template, drag the circles or edit the homography matrix below:
</div>
<div class="separator"></div>
<div>
<table>
<tr>
<td><input type="number" step="0.1" id="homography-0" value="1"></td>
<td><input type="number" step="0.1" id="homography-3" value="0"></td>
<td><input type="number" step="0.1" id="homography-6" value="0"></td>
</tr>
<tr>
<td><input type="number" step="0.1" id="homography-1" value="0"></td>
<td><input type="number" step="0.1" id="homography-4" value="1"></td>
<td><input type="number" step="0.1" id="homography-7" value="0"></td>
</tr>
<tr>
<td><input type="number" step="0.1" id="homography-2" value="0"></td>
<td><input type="number" step="0.1" id="homography-5" value="0"></td>
<td><input type="number" step="0.1" id="homography-8" value="1"></td>
</tr>
</table>
</div>
</form>
<div>
<span id="status"></span>
<canvas id="canvas-demo"></canvas>
</div>
<div>
<button id="play">Play / pause</button>
</div>
<video
src="../assets/flying-eagle.webm"
poster="../assets/loading.jpg"
preload="auto"
loop muted hidden
title="Free video by Cinema Professionals, https://www.pexels.com/pt-br/video/assistindo-a-aguia-voar-3635378/">
</video>
<script>
const VERTEX_RADIUS = 5;
const vertices = [
{ x: 0, y: 0, drag: false },
{ x: 0, y: 0, drag: false },
{ x: 0, y: 0, drag: false },
{ x: 0, y: 0, drag: false }
];
const mouse = { x: 0, y: 0, drag: false };
const template = {
// matrices are specified in column-major format
"Identity":
[
1, 0, 0, // 1st column
0, 1, 0, // 2nd column
0, 0, 1, // 3rd column
],
"Flip":
[
-1, 0, 0,
0, 1, 0,
639, 0, 1,
],
"Scale":
[
0.5, 0, 0,
0, 0.5, 0,
0, 0, 1,
],
"Translation":
[
0.5, 0, 0,
0, 0.5, 0,
200, 100, 1,
],
"Rotation":
[
0.86, 0.5, 0,
-0.5, 0.86, 0,
400, 50, 2,
],
"Shear":
[
0.5, 0, 0,
-0.5, 0.5, 0,
250, 100, 1,
],
"Perspective":
[
0.2, 0, 0,
-0.5, -0.15, -0.0015,
280, 180, 1,
],
};
window.onload = async function()
{
// load a video
const video = document.querySelector('video');
const media = await Speedy.load(video);
video.play();
// create a canvas
const canvas = createCanvas(media.width, media.height, video.title);
// create the pipeline
const pipeline = Speedy.Pipeline();
const source = Speedy.Image.Source();
const sink = Speedy.Image.Sink();
const perspective = Speedy.Transform.PerspectiveWarp();
source.media = media;
source.output().connectTo(perspective.input());
perspective.output().connectTo(sink.input());
pipeline.init(source, sink, perspective);
// input fields
const homographyElement = [...(new Array(9)).keys()].map(k => document.getElementById('homography-' + k));
// setup the <select> element
const templateSelector = document.getElementById('template');
for(let templateName in template) {
const option = document.createElement('option');
const text = document.createTextNode(templateName);
option.value = templateName;
option.selected = (option.value == 'Identity');
option.appendChild(text);
templateSelector.appendChild(option);
}
templateSelector.onchange = () => {
const name = templateSelector.value;
homographyElement.forEach((inputField, i) => inputField.value = template[name][i]);
syncVertices();
};
// sync the vertices
async function syncVertices()
{
const homography = Speedy.Matrix(3, 3, homographyElement.map(k => +k.value));
const src = Speedy.Matrix(2, 4, [
0, 0,
canvas.width, 0,
canvas.width, canvas.height,
0, canvas.height
]);
const dest = Speedy.Matrix.Zeros(2, 4);
await Speedy.Matrix.applyPerspectiveTransform(dest, src, homography);
for(let i = 0; i < dest.columns; i++) {
vertices[i].x = dest.at(0, i);
vertices[i].y = dest.at(1, i);
}
}
homographyElement.map(el => el.oninput = syncVertices);
syncVertices(); // initialize vertices
// update vertices
async function updateVertices()
{
// drag the vertices
const r2 = VERTEX_RADIUS * VERTEX_RADIUS;
let anydrag = vertices.reduce((d, v) => d || v.drag, false);
let anyhover = false;
for(const vertex of vertices) {
const dx = mouse.x - vertex.x;
const dy = mouse.y - vertex.y;
const nearby = (dx * dx + dy * dy <= r2);
if(!anydrag && mouse.drag && nearby)
anydrag = vertex.drag = true;
anyhover = anyhover || nearby;
if(vertex.drag) {
if((vertex.drag = mouse.drag)) {
vertex.x = mouse.x;
vertex.y = mouse.y;
}
}
}
canvas.style.cursor = anydrag || anyhover ? 'pointer' : 'auto';
// if we're dragging the vertices,
// compute a new homography
if(anydrag) {
const src = Speedy.Matrix(2, 4, [
0, 0,
canvas.width, 0,
canvas.width, canvas.height,
0, canvas.height
]);
const dest = Speedy.Matrix(2, 4,
vertices.reduce((entries, v) => entries.concat([v.x, v.y]), [])
);
const homography = Speedy.Matrix.Zeros(3, 3);
await Speedy.Matrix.perspective(homography, src, dest);
const entries = homography.read();
for(let i = 0; i < entries.length; i++)
homographyElement[i].value = entries[i];
}
// update the pipeline
const homography = Speedy.Matrix(3, 3, homographyElement.map(k => Number(k.value)));
perspective.transform = homography;
// loop
setTimeout(updateVertices, 1000 / 60);
}
updateVertices();
// Main loop
(function() {
let image = null, frameReady = false;
const context = canvas.getContext('2d');
context.fillStyle = '#ff0';
context.strokeStyle = '#f00';
context.lineWidth = 2;
async function update()
{
const result = await pipeline.run();
image = result.image;
frameReady = true;
setTimeout(update, 1000 / 60);
}
update();
function render()
{
if(frameReady) {
// render the warped image
draw(image, canvas);
// render the vertices
const TWO_PI = Math.PI * 2;
context.beginPath();
for(const vertex of vertices) {
context.moveTo(vertex.x + VERTEX_RADIUS, vertex.y);
context.arc(vertex.x, vertex.y, VERTEX_RADIUS, 0, TWO_PI);
}
context.fill();
context.stroke();
}
frameReady = false;
requestAnimationFrame(render);
}
render();
setInterval(renderStatus, 200);
})();
// play/pause
const playButton = document.getElementById('play');
playButton.onclick = () => video.paused ? video.play() : video.pause();
}
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);
canvas.addEventListener('mousedown', ev => {
const position = cursorPosition(canvas, ev);
mousedrag(position.x, position.y, width, height, true);
});
canvas.addEventListener('mouseup', ev => {
const position = cursorPosition(canvas, ev);
mousedrag(position.x, position.y, width, height, false);
});
canvas.addEventListener('mousemove', ev => {
const position = cursorPosition(canvas, ev);
mousedrag(position.x, position.y, width, height);
});
return canvas;
}
function renderStatus()
{
const status = document.getElementById('status');
status.innerText = `FPS: ${Speedy.fps}`;
}
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);
}
function cursorPosition(canvas, event)
{
const rect = canvas.getBoundingClientRect();
const x = event.clientX - rect.left;
const y = event.clientY - rect.top;
return { x, y };
}
function mousedrag(x, y, width, height, drag)
{
if(drag !== undefined)
mouse.drag = drag;
if(x >= 0 && x < width)
mouse.x = x;
if(y >= 0 && y < height)
mouse.y = y;
}
</script>
<mark>Powered by <a href="https://github.com/alemart/speedy-vision">speedy-vision.js</a></mark>
</body>
</html>