habana_frameworks.mediapipe.fn.Normalize

Class:

• habana_frameworks.mediapipe.fn.Normalize(**kwargs)

Define graph call:

• __call__(input)

Parameter:

• input - Input tensor to operator. Supported dimensions: minimum = 4, maximum = 4. Supported data types: UINT8, UINT16.

Description:

Normalizes the input tensor by subtracting mean and dividing by standard deviation. The mean and stddev are calculated internally. Normalization is done using the formula given below. Epsilon(1e-05) is added in order to avoid division by 0.

out = (scale * (in - mean)) / sqrt(variance + epsilon) + shift

Supported backend:

• HPU

Keyword Arguments

kwargs	Description
scale	Scaling factor to be applied to output. Type: float Default: 0.0 Optional: yes
shift	The value to which mean will map to the output. Type: float Default: 0.0 Optional: yes
axis	An optional bitmap for CHW data layout. Set res bit for the dim to be normalized. Type: int Default: 0 Optional: yes Supported values: 0, 1, 2, 3, 4, 5, 7
batch	If set to True, the mean and standard deviation are calculated across tensors in the batch. This argument is not yet supported by TPC kernel. Type: bool Default: false Optional: yes
dtype	Ouptput data type. Type: habana_frameworks.mediapipe.media_types.dtype Default: UINT8 Optional: yes Supported data types: UINT8 UINT16

Note

1. When number of input tensor = 1, i.e., only ifm is provided and the axis is also set to default value, i.e. 0 then normalization is done along CHW.

2. If either of mean or inverse standard deviation tensor is given as input and along with that axis is also specified then the shape of mean/inverse standard deviation tensor should match the reduced input tensor shape based on axis. Currently attribute axis can take the following values - 1, 2, 3, 4, 5 and 7.

Example: Normalize Operator

The following code snippet shows usage of Normalize operator:

from habana_frameworks.mediapipe import fn
from habana_frameworks.mediapipe.mediapipe import MediaPipe
from habana_frameworks.mediapipe.media_types import imgtype as it
from habana_frameworks.mediapipe.media_types import dtype as dt
import matplotlib.pyplot as plt

# Create media pipeline derived class
class myMediaPipe(MediaPipe):
    def __init__(self, device, dir, queue_depth, batch_size, img_h, img_w):
        super(
            myMediaPipe,
            self).__init__(
            device,
            queue_depth,
            batch_size,
            self.__class__.__name__)

        self.input = fn.ReadImageDatasetFromDir(shuffle=False,
                                                dir=dir,
                                                format="jpg")

        # WHCN
        self.decode = fn.ImageDecoder(device="hpu",
                                      output_format=it.RGB_P,
                                      resize=[img_w, img_h])

        self.normalize = fn.Normalize(scale=60.0,
                                      shift=120.0,
                                      axis=1)

        # WHCN -> CWHN
        self.transpose = fn.Transpose(permutation=[2, 0, 1, 3],
                                      tensorDim=4,
                                      dtype=dt.UINT8)

    def definegraph(self):
        images, labels = self.input()
        images = self.decode(images)
        images = self.normalize(images)
        images = self.transpose(images)
        return images, labels

def display_images(images, batch_size, cols):
    rows = (batch_size + 1) // cols
    plt.figure(figsize=(10, 10))
    for i in range(batch_size):
        ax = plt.subplot(rows, cols, i + 1)
        plt.imshow(images[i])
        plt.axis("off")
    plt.show()

def main():
    batch_size = 6
    img_width = 200
    img_height = 200
    img_dir = "/path/to/images"
    queue_depth = 2
    columns = 3

    # Create media pipeline object
    pipe = myMediaPipe('hpu', img_dir, queue_depth, batch_size,
                        img_height, img_width)

    # Build media pipeline
    pipe.build()

    # Initialize media pipeline iterator
    pipe.iter_init()

    # Run media pipeline
    images, labels = pipe.run()

    # Copy data to host from device as numpy array
    images = images.as_cpu().as_nparray()
    labels = labels.as_cpu().as_nparray()

    # Display images
    display_images(images, batch_size, columns)


if __name__ == "__main__":
    main()

Normalized Images 1

1

Licensed under a CC BY SA 4.0 license. The images used here are taken from https://data.caltech.edu/records/mzrjq-6wc02.