Function fromPixelsAsync

tfjs-core/src/ops/browser.ts:227–270

(
    pixels: PixelData|ImageData|HTMLImageElement|HTMLCanvasElement|
    HTMLVideoElement|ImageBitmap,
    numChannels = 3)

 * @doc {heading: 'Browser', namespace: 'browser', ignoreCI: true}
 */
export async function fromPixelsAsync(
    pixels: PixelData|ImageData|HTMLImageElement|HTMLCanvasElement|
    HTMLVideoElement|ImageBitmap,
    numChannels = 3) {
  let inputs: PixelData|ImageData|HTMLImageElement|HTMLCanvasElement|
      HTMLVideoElement|ImageBitmap = null;

  // Check whether the backend needs to wrap |pixels| to imageBitmap and
  // whether |pixels| can be wrapped to imageBitmap.
  if (env().getBool('WRAP_TO_IMAGEBITMAP') &&
      canWrapPixelsToImageBitmap(pixels)) {
    // Force the imageBitmap creation to not do any premultiply alpha
    // ops.
    let imageBitmap;

    try {
      // wrap in try-catch block, because createImageBitmap may not work
      // properly in some browsers, e.g.
      // https://bugzilla.mozilla.org/show_bug.cgi?id=1335594
      // tslint:disable-next-line: no-any
      imageBitmap = await (createImageBitmap as any)(
          pixels as ImageBitmapSource, {premultiplyAlpha: 'none'});
    } catch (e) {
      imageBitmap = null;
    }

    // createImageBitmap will clip the source size.
    // In some cases, the input will have larger size than its content.
    // E.g. new Image(10, 10) but with 1 x 1 content. Using
    // createImageBitmap will clip the size from 10 x 10 to 1 x 1, which
    // is not correct. We should avoid wrapping such resouce to
    // imageBitmap.
    if (imageBitmap != null && imageBitmap.width === pixels.width &&
        imageBitmap.height === pixels.height) {
      inputs = imageBitmap;
    } else {
      inputs = pixels;
    }
  } else {
    inputs = pixels;
  }

  return fromPixels_(inputs, numChannels);
}

function validateImgTensor(img: Tensor2D|Tensor3D) {
  if (img.rank !== 2 && img.rank !== 3) {