message: Update the comment for the normalization parameters
diff: @@ -317,12 +317,22 @@ table NormalizationOptions{
  // mean and std are normalization parameters. Tensor values are normalized
  // on a per-channel basis, by the formula
  // (x - mean) / std.
  - // For example, a float MobileNet model will have
  - // mean = 127.5f and std = 127.5f.
  - // A quantized MobileNet model will have
  - // mean = 0.0f and std = 1.0f.
  // If there is only one value in mean or std, we'll propogate the value to
  // all channels.
  + //
  + // Quantized models share the same normalization parameters as their
  + // corresponding float models. For example, an image input tensor may have
  + // the normalization parameter of
  + // mean = 127.5f and std = 127.5f.
  + // The image value will be normalized from [0, 255] to [-1, 1].
  + // Then, for quantized models, the image data should be further quantized
  + // according to the quantization parameters. In the case of uint8, the image
  + // data will be scaled back to [0, 255], while for int8, the image data will
  + // be scaled to [-128, 127].
  + //
  + // Both the normalization parameters and quantization parameters can be
  + // retrieved through the metadata extractor library.
  + // TODO(b/156644598): add link for the metadata extractor library.
  // Per-channel mean of the possible values used in normalization.
  //
  