habana_frameworks.mediapipe.fn.Pad

Class:

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

Define graph call:

• __call__(input)

Parameter:

• input - Input tensor to operator. Supported dimensions: minimum = 1, maximum = 5. Supported data types: INT8, UINT8, BFLOAT16, FLOAT32.

Description:

Pads a tensor with zeros or any numbers. Output tensor size is calculated using the following formula:

• For 4D tensors:

  out_sizes[0] = input_sizes[0] + pads[0] + pads[4]

  out_sizes[1] = input_sizes[1] + pads[1] + pads[5]

  out_sizes[2] = input_sizes[2] + pads[2] + pads[6]

  out_sizes[3] = input_sizes[3] + pads[3] + pads[7]

• For 5D tensors:

  out_sizes[0] = input_sizes[0] + pads[0] + pads[5]

  out_sizes[1] = input_sizes[1] + pads[1] + pads[6]

  out_sizes[2] = input_sizes[2] + pads[2] + pads[7]

  out_sizes[3] = input_sizes[3] + pads[3] + pads[8]

  out_sizes[4] = input_sizes[4] + pads[4] + pads[9]

Supported backend:

• HPU

Keyword Arguments

kwargs	Description
mode	Specifies padding mode. Type: PadMode_t Default: 0 Optional: yes Supported types: PAD_MODE_CONSTANT(0): Pads value with a given constant as specified by constant value. PAD_MODE_REFLECT(1) Pads with the mirror values of the array leaving edge values. PAD_MODE_EDGE(2): Pads with the edge values of array. PAD_MODE_SYMMETRIC(3): Pads with the mirror values of the array.
value	A constant to pad the input. Type: float Default: 0.0 Optional: yes
pads[10]	The paddings indicate how many constant values to add before and after the input in all the dimensions given as pad_before[0]…pad_before[4], pad_after[0] … pad_after[4]. Type: list[int] Default: 0 Optional: yes
dtype	Output data type. Type: habana_frameworks.mediapipe.media_types.dtype Default: UINT8 Optional: yes Supported data types: INT8 UINT8 FLOAT32

Note

1. Input/Output tensors datatype should match operation data type.

2. In PAD_MODE_SYMMETRIC, pad along a dim should not be greater than corresponding dim size.

3. In PAD_MODE_REFLECT, pad along a dim should not be greater or equal to corresponding dim size.

4. Negative pads are only supported in Constant mode.

5. “PAD_MODE_EDGE” mode is ONNX compliant.

Example: Pad Operator

The following code snippet shows usage of Pad 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.pad = fn.Pad(pads=[60, 30, 0, 0, 60, 30, 0, 0],
                          mode=0,
                          value=0.0,
                          dtype=dt.UINT8)

        # 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.pad(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 shape
    display_images(images, batch_size, columns)


if __name__ == "__main__":
    main()

Images with Padding by Constant Value 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.