Simple Image Encode

[fisker]

function reverseImage(image) {
  const canvas  = document.createElement('canvas')
  const {width, height} = image
  Object.assign(canvas, {width, height})
  const context= canvas.getContext('2d')
  context.drawImage(image, 0, 0)
  const {data} = context.getImageData(0, 0, width, height)
  const imageData = new ImageData(
    new Uint8ClampedArray(
      Array.from(data).map(x => 255 - x).reverse()
    ), 
    height, 
    width
  )

  Object.assign(canvas,{width: height, height: width})
  context.putImageData(imageData, 0, 0)
  return canvas
}

function simpleImageEncode(imageUrl) {
  return new Promsie(resolve => {
    const image = new Image()
    image.src = imageUrl
    image.onload = () => {
      resolve(reverseImage(image))
    }
  })
}

Update: not safe, alpha value postion can't change, will lost color, should only switch postion of rgb value