processing QrCode from opencv capture

[pedefe]

Hello, I get my image from 'opencv'. Something like :

const cv = require("opencv");
const QrCode = require('qrcode-reader');
var qr = new QrCode();
qr.callback = function(err, result) {
	...
}
...
var camera = new cv.VideoCapture(0);
camera.read( function(err, im) {
	if (err) {
		log(`VideoCapture > err: ${err}`);
	} else {
		... how to convert 'im' to bitmap... ?
		qr.decode( bitmap);

So, how to convert 'opencv' acquisition for qr processing ? Best regards ?