text: // Load an image from a preloaded file
  // Image source: https://www.flickr.com/photos/jasonidzerda/3987784466
  let im = vips.Image.newFromFile('owl.jpg', {
      access: vips.Access.sequential /*'sequential'*/
  });
  
  // Optionally, convert to greyscale
  // im = im.colourspace(vips.Interpretation.b_w/*'b-w'*/);
  
  // Apply sobel operator
  im = im.sobel();
  
  // Finally, write the result to a blob
  const t0 = performance.now();
  const outBuffer = new Uint8Array(im.writeToBuffer('.jpg'));
  const t1 = performance.now();
  
  console.log(`Call to writeToBuffer took ${t1 - t0} milliseconds.`);
  
  const blob = new Blob([outBuffer], {type: 'image/jpeg'});
  const blobURL = URL.createObjectURL(blob);
  const img = document.createElement('img');
  img.src = blobURL;
  document.getElementById('output').appendChild(img);
  