基于webassembly 的opencv nodejs 开发是一个很不错的体验，不用考虑node addon 的各种问题，而且性能也不错
以下是基于echamudi/opencv-wasm 构建的4.8.1 版本的试用，代码来自opencv-wasm 的示例demo
试用
- pacakge.json
{
"name": "opencv-wasm",
"version": "1.0.0",
"main": "index.js",
"license": "MIT",
"dependencies": {
"@dalongrong/opencv-wasm": "^4.8.1-1",
"jimp": "^0.22.10"
}
}"name": "opencv-wasm",- demo.js
主要是基于opencv 进行特征匹配，然后进行框选标记
const Jimp = require('jimp');
const { cv, cvTranslateError } = require('@dalongrong/opencv-wasm'); // replace with require('opencv-wasm') in prod
(async () => {
try {
const imageSource = await Jimp.read(__dirname + '/image-sample-2.png');
const imageTemplate = await Jimp.read(__dirname + '/image-sample-2-template.png');
let src = cv.matFromImageData(imageSource.bitmap);
let templ = cv.matFromImageData(imageTemplate.bitmap);
let processedImage = new cv.Mat();
let mask = new cv.Mat();
cv.matchTemplate(src, templ, processedImage, cv.TM_CCOEFF_NORMED, mask);
cv.threshold(processedImage, processedImage, 0.999, 1, cv.THRESH_BINARY);
processedImage.convertTo(processedImage, cv.CV_8UC1);
let contours = new cv.MatVector();
let hierarchy = new cv.Mat();
cv.findContours(processedImage, contours, hierarchy, cv.RETR_EXTERNAL, cv.CHAIN_APPROX_SIMPLE);
for (let i = 0; i < contours.size(); ++i) {
let countour = contours.get(i).data32S; // Contains the points
let x = countour[0];
let y = countour[1];
let color = new cv.Scalar(0, 255, 0, 255);
let pointA = new cv.Point(x, y);
let pointB = new cv.Point(x + templ.cols, y + templ.rows);
cv.rectangle(src, pointA, pointB, color, 2, cv.LINE_8, 0);
}
new Jimp({
width: src.cols,
height: src.rows,
data: Buffer.from(src.data)
})
.write(__dirname + '/template-matching.png');
} catch (err) {
console.log(cvTranslateError(cv, err));
}
})();const { cv, cvTranslateError } = require('@dalongrong/opencv-wasm'); // replace with require('opencv-wasm') in prod效果
说明
基于webassembly 版本的opencv 可以方便进行nodejs 的图像处理，目前不太好的是对于ts 的提示支持的不太好，可以自己开发
参考资料
https://github.com/jimp-dev/jimp
https://github.com/echamudi/opencv-wasm
https://www.npmjs.com/package/@dalongrong/opencv-wasm
https://github.com/rongfengliang/opencv_waam_learning