cvMat, cvImage and cvRect serialization

[erenaud3]

Hi !

Is it possible to serialize variables of type cvMat, cvImage or cvRect ?

I'm currently trying to design a system with several NodeJs programs where one master is performing facial detection while some slaves receive frames in order to perform further processing (landmarks, facial recognition,...).

Thanks for your help !

[Chuiantw1212]

What is the application for?
I presume that you want to detect faces from stream or videos?

[erenaud3]

Yeah sorry I didn't precise it.
You're absolutely right, the goal is to detect (and later recognize) faces from a webcam stream.

For the moment, I'm using a folder when I am saving the frames I want my workers to work on. But it doesn't seem to be the best approached.

[Chuiantw1212]

Using a folder, like by fs?

[erenaud3]

Using a folder, like by fs?

Exactly

[Chuiantw1212]

const cv = require('opencv4nodejs')
const fr = require("face-recognition").withCv(cv)

function extractFace(htmlImageSrc) {
let result = null
const base64data = htmlImageSrc.replace('data:image/jpeg;base64', '')
.replace('data:image/png;base64', '')
const buffer = Buffer.from(base64data, 'base64')
const mat = cv.imdecode(buffer)
const cvImage = fr.CvImage(mat)
const frImage = fr.cvImageToImageRGB(cvImage)
const facesExtracted = this.detectFace(frImage)
if (facesExtracted) {
fr.saveImage(Models/image/${image.name}.png, facesExtracted.toGray())
result = facesExtracted
}
return result
}

Not sure if this is what your looking for though.

[erenaud3]

Thank you for your help !

const base64data = image.src.replace('data:image/jpegbase64', '')

This line seems strange to me though. What is the type of "image" ? cvImage ?

It's not working for me with my image variable, which I'm getting like this :

cap = new cv.VideoCapture(videoDeviceId);
(...)
image = cap.read();

EDIT: By "not working", I mean that image.src is undefined.

[Chuiantw1212]

@erenaud3 Oh, it was my stuff. You can just remove the ".src" part,
the only thing matters is to make variable base64data stores the base64 image data.

[erenaud3]

Not sure if this is what your looking for though.

In deed, it's a good start but the problem is I don't know how to get the base64 text from my cvImage.

[erenaud3]

Okay so there's one thing I failed to understand at first: what I'm getting with capture.read() is a cvMat and not a cvImage. Which led me to the functions i was looking for:
cv.imencode() and cv.imdecode()

But now I have a problem with those functions as well. I am opening a new issue.