generate area on image in javascript

index.tsx
// Load an image
var img = new Image();
img.src = 'path/to/image.jpg';

// Wait for the image to load
img.onload = function() {
  // Create a canvas element with the same dimensions as the image
  var canvas = document.createElement('canvas');
  canvas.width = img.width;
  canvas.height = img.height;
  var ctx = canvas.getContext('2d');

  // Draw the image onto the canvas
  ctx.drawImage(img, 0, 0);

  // Get the pixel data for the entire image
  var imageData = ctx.getImageData(0, 0, canvas.width, canvas.height);
  var pixels = imageData.data;

  // Apply a threshold to generate a binary mask
  var threshold = 128;
  for (var i = 0; i < pixels.length; i += 4) {
    // Convert RGB to grayscale using the luminosity method
    var gray = 0.21 * pixels[i] + 0.72 * pixels[i+1] + 0.07 * pixels[i+2];
    if (gray > threshold) {
      // White pixel
      pixels[i] = 255;
      pixels[i+1] = 255;
      pixels[i+2] = 255;
    } else {
      // Black pixel
      pixels[i] = 0;
      pixels[i+1] = 0;
      pixels[i+2] = 0;
    }
    // Alpha value remains unchanged
  }

  // Put the modified pixel data back onto the canvas
  ctx.putImageData(imageData, 0, 0);

  // The canvas now contains a binary mask of the image
  // Areas of interest correspond to white pixels
};
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