n {TestCanvas}
     *
     * @typedef {Object} TestCanvas
     * @property {CanvasRenderingContext2D} ctx
     * @property {ImageData} imageData
     */
    function genRandomNoise (width, height) {
      const canvas = document.createElement('canvas')
      canvas.width = width
      canvas.height = height
      const ctx = canvas.getContext('2d')
      // Create a grid of random colors
      const imageData = ctx.createImageData(canvas.width, canvas.height)
      // opaque so premultiplied alpha won't mes