gistlib - image processing wavelet transforms matlab in javascript

To perform image processing using wavelet transforms in JavaScript, you can use libraries such as jimp or opencv.js. However, implementing wavelet transforms from scratch can be a complex task. Here's an example of how you can achieve this using JavaScript:


index.tsx
// Define a 2D array to hold the image data
let imageData = [
  [1, 2, 3, 4],
  [5, 6, 7, 8],
  [9, 10, 11, 12],
  [13, 14, 15, 16]
];

// Define a function to perform the DWT (Discrete Wavelet Transform)
function dwt(imageData) {
  let dwtImageData = [];
  for (let i = 0; i < imageData.length; i += 2) {
    let row = [];
    for (let j = 0; j < imageData[i].length; j += 2) {
      // Calculate the average (approximation coefficient)
      let avg = (imageData[i][j] + imageData[i + 1][j] + imageData[i][j + 1] + imageData[i + 1][j + 1]) / 4;
      row.push(avg);
    }
    dwtImageData.push(row);
  }
  return dwtImageData;
}

// Define a function to perform the IDWT (Inverse Discrete Wavelet Transform)
function idwt(dwtImageData) {
  let idwtImageData = [];
  for (let i = 0; i < dwtImageData.length; i++) {
    let row = [];
    for (let j = 0; j < dwtImageData[i].length; j++) {
      // Calculate the pixel values using the approximation coefficient
      let avg = dwtImageData[i][j];
      row.push(avg);
      row.push(avg);
    }
    idwtImageData.push(row);
    let newRow = [];
    for (let j = 0; j < dwtImageData[i].length; j++) {
      newRow.push(avg);
      newRow.push(avg);
    }
    idwtImageData.push(newRow);
  }
  return idwtImageData;
}

// Perform the DWT
let dwtImageData = dwt(imageData);
console.log('DWT:', dwtImageData);

// Perform the IDWT
let idwtImageData = idwt(dwtImageData);
console.log('IDWT:', idwtImageData);
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Note that this is a simplified example and actual implementation of wavelet transforms involves more complex calculations and filters.

To work with images in JavaScript, you would need to use a library that can handle image data, such as jimp or opencv.js. Here's an example using jimp:


index.tsx
const Jimp = require('jimp');

// Load an image
Jimp.read('image.jpg', (err, image) => {
  if (err) throw err;
  // Get the image data
  let imageData = image.bitmap.data;
  // Perform the DWT or IDWT using the above functions
  // ...
});
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Remember to install the required libraries using npm or yarn:


npm install jimp opencv.js
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Or using yarn:


yarn add jimp opencv.js
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image processing wavelet transforms matlab in javascript

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