如何使用 opencv.js 屏蔽图像的一部分

Question

What seems to be a simple step in OpenCV in python turns out a hurdle in opencv.js. I am trying to mask a section on image with white color, reference image below. In Python it is super simple.

below is the line of code in python:

image = cv.imread('imagefile')
x = 180
y = 180
w = 70
h = 35
image[(y+h):y, x:(x+w)] = [255, 255, 255]

Here image[(y+h):y, x:(x+w)] = [255, 255, 255] is doing the trick of masking the part of the image with white color

Could someone help me how to achieve this in opencv.js
below is code in java script.

let img = cv.imread('imagefile')
let x = 180
let y = 180
let w = 70
let h = 35
let image_width = 511
let image_height = 511
---
what should be the code here to achieve the desired result

Answer 1

You can used cv.rectangle to draw the filled white rectangle to achieve this result:

let mat = cv.imread(imgElement);
let point1 = new cv.Point(240, 240);
let point2 = new cv.Point(360, 290);
cv.rectangle(mat, point1, point2, [255, 255, 255, 255], -1);
cv.imshow('canvasOutput', mat);
mat.delete();