How to recognize camera data stream images

[zyqq]

I preprocess imgData like this

 const imgData = {data: new Uint8Array(frame.data), width: frame.width, height: frame.height}
    return tf.tidy(() => {
        var tensor = tf.browser.fromPixels(imgData, 1)
        const resized = tf.image.resizeBilinear(tensor, [28, 28]).toFloat()
        const offset = tf.scalar(255.0);
        const normalized = tf.scalar(1.0).sub(resized.div(offset));
        const batched = normalized.expandDims(0)
        return batched
   }

but it doesn't work right. Did I make a mistake?